diff --git "a/src/main/kotlin/hyunsoo/54week/\353\254\270\354\236\220\354\227\264 \352\262\214\354\236\204 2.kt" "b/src/main/kotlin/hyunsoo/54week/\353\254\270\354\236\220\354\227\264 \352\262\214\354\236\204 2.kt"
new file mode 100644
index 00000000..c9bb341f
--- /dev/null
+++ "b/src/main/kotlin/hyunsoo/54week/\353\254\270\354\236\220\354\227\264 \352\262\214\354\236\204 2.kt"	
@@ -0,0 +1,98 @@
+package hyunsoo.`54week`
+
+/**
+ *
+ * <문제>
+ * [문자열 게임 2](https://www.acmicpc.net/problem/20437)
+ *
+ * - 아이디어
+ *
+ * - 트러블 슈팅
+ *
+ */
+class `전현수_문자열_게임_2` {
+
+    val br = System.`in`.bufferedReader()
+
+    private data class CharWithIndex(val char: Char, val index: Int)
+
+    fun solution() {
+
+        val t = br.readLine().toInt()
+
+        repeat(t) {
+
+            var firstConditionResult = Int.MAX_VALUE
+            var secondConditionResult = -1
+
+            val w = br.readLine()
+            val k = br.readLine().toInt()
+
+            val alphabetCounter = IntArray(26)
+            val validCharList = mutableSetOf<Char>()
+
+            val validCharInfoList = mutableListOf<CharWithIndex>()
+
+            if (k == 1) {
+                println("1 1")
+                return@repeat
+            }
+
+            w.forEachIndexed { index, char ->
+                val curCharCnt = ++alphabetCounter[char.toSequence()]
+                if (k <= curCharCnt)
+                    validCharList.add(char)
+            }
+
+            w.forEachIndexed { index, char ->
+                if (validCharList.contains(char)) {
+                    validCharInfoList.add(CharWithIndex(char, index))
+                }
+            }
+
+            val sortedValidCharInfoList = validCharInfoList
+                .sortedWith(
+                    compareBy<CharWithIndex> { it.char }
+                        .thenBy { it.index }
+                )
+
+            for (i in sortedValidCharInfoList.indices) {
+
+                val (target, startIndex) = sortedValidCharInfoList[i]
+                var targetIncludedCnt = 1
+
+                for (j in i + 1 until sortedValidCharInfoList.size) {
+
+                    val (endTarget, endIndex) = sortedValidCharInfoList[j]
+                    if (target != endTarget) {
+                        break
+                    }
+                    targetIncludedCnt++
+                    if (k != targetIncludedCnt) continue
+
+                    val curLength = endIndex - startIndex + 1
+
+                    if (curLength < firstConditionResult) firstConditionResult = curLength
+                    if (secondConditionResult < curLength) secondConditionResult = curLength
+
+                }
+            }
+
+            if (firstConditionResult == Int.MAX_VALUE || secondConditionResult == -1) {
+                println(-1)
+            } else {
+                println("$firstConditionResult $secondConditionResult")
+            }
+
+        }
+    }
+
+    private fun Char.toSequence(): Int {
+        return this.code - 97
+    }
+
+}
+
+fun main() {
+    전현수_문자열_게임_2().solution()
+}
\ No newline at end of file
diff --git "a/src/main/kotlin/hyunsoo/54week/\354\232\260\354\262\264\352\265\255.kt" "b/src/main/kotlin/hyunsoo/54week/\354\232\260\354\262\264\352\265\255.kt"
new file mode 100644
index 00000000..84e6d0c7
--- /dev/null
+++ "b/src/main/kotlin/hyunsoo/54week/\354\232\260\354\262\264\352\265\255.kt"
@@ -0,0 +1,53 @@
+package hyunsoo.`54week`
+
+/**
+ *
+ * <문제>
+ * [우체국](https://www.acmicpc.net/problem/2141)
+ *
+ * - 아이디어
+ *
+ * - 트러블 슈팅
+ *
+ */
+class `전현수_우체국` {
+
+    private data class VillageInfo(val villageNum: Long, val peopleCnt: Long)
+
+    private val villageInfoList = mutableListOf<VillageInfo>()
+
+    fun solution() {
+
+        var totalPeopleCnt = 0L
+        var prefixSumOfPeopleCnt = 0L
+        val n = readln().toInt()
+
+        repeat(n) {
+
+            val (villageNum, peopleCnt) = readln().split(" ").map { it.toLong() }
+            villageInfoList.add(VillageInfo(villageNum, peopleCnt))
+            totalPeopleCnt += peopleCnt
+
+        }
+
+        val mid = if (totalPeopleCnt % 2 == 0L) totalPeopleCnt / 2 else totalPeopleCnt / 2 + 1
+
+        villageInfoList
+            .sortedBy { it.villageNum }
+            .forEach {
+
+                val (vil, curPeopleCnt) = it
+
+                prefixSumOfPeopleCnt += curPeopleCnt
+
+                if (mid <= prefixSumOfPeopleCnt) {
+                    println(vil)
+                    return
+                }
+            }
+    }
+}
+
+fun main() {
+    전현수_우체국().solution()
+}
\ No newline at end of file
diff --git "a/src/main/kotlin/hyunsoo/54week/\355\206\240\353\247\210\355\206\240.kt" "b/src/main/kotlin/hyunsoo/54week/\355\206\240\353\247\210\355\206\240.kt"
new file mode 100644
index 00000000..6037d5d9
--- /dev/null
+++ "b/src/main/kotlin/hyunsoo/54week/\355\206\240\353\247\210\355\206\240.kt"
@@ -0,0 +1,87 @@
+package hyunsoo.`54week`
+
+import java.util.LinkedList
+import java.util.Queue
+
+/**
+ *
+ * <문제>
+ * [토마토](https://www.acmicpc.net/problem/7576)
+ *
+ * - 아이디어
+ *
+ * - 트러블 슈팅
+ *
+ */
+class `전현수_토마토` {
+
+    private data class Position(val x: Int, val y: Int)
+
+    private val dirs = listOf(
+        Position(0, -1),
+        Position(-1, 0),
+        Position(0, 1),
+        Position(1, 0),
+    )
+
+    private data class QueueData(val pos: Position, val day: Int)
+
+    private val box = mutableListOf<MutableList<Int>>()
+    private val startPositionList = mutableListOf<Position>()
+
+    fun solution() {
+
+        val queue: Queue<QueueData> = LinkedList()
+
+        val (n, m) = readln().split(" ").map { it.toInt() }
+
+        repeat(m) { rowIndex ->
+            val row = readln().split(" ")
+                .mapIndexed { columnIndex, it ->
+                    if (it == "1") startPositionList.add(Position(rowIndex, columnIndex))
+                    it.toInt()
+                } as MutableList
+            box.add(row)
+        }
+
+        startPositionList.forEach {
+            queue.add(QueueData(it, 1))
+        }
+
+        while (queue.isNotEmpty()) {
+
+            val (curPos, curDay) = queue.poll()
+
+            dirs.forEach { dir ->
+
+                val nx = curPos.x + dir.x
+                val ny = curPos.y + dir.y
+
+                if (nx !in 0 until m ||
+                    ny !in 0 until n
+                ) return@forEach
+
+                if (box[nx][ny] == 0) {
+
+                    box[nx][ny] = curDay + 1
+                    queue.add(QueueData(Position(nx, ny), curDay + 1))
+
+                }
+            }
+        }
+
+        val result = box.flatten()
+
+        if (result.contains(0)) {
+            println(-1)
+        } else {
+            println(result.maxOf { it } - 1)
+        }
+
+    }
+
+}
+
+fun main() {
+    전현수_토마토().solution()
+}
\ No newline at end of file
diff --git "a/src/main/kotlin/hyunsoo/54week/\355\225\255\354\262\264 \354\235\270\354\213\235.kt" "b/src/main/kotlin/hyunsoo/54week/\355\225\255\354\262\264 \354\235\270\354\213\235.kt"
new file mode 100644
index 00000000..98b07ac9
--- /dev/null
+++ "b/src/main/kotlin/hyunsoo/54week/\355\225\255\354\262\264 \354\235\270\354\213\235.kt"	
@@ -0,0 +1,104 @@
+package hyunsoo.`54week`
+
+import kotlin.system.exitProcess
+
+/**
+ *
+ * <문제>
+ * [항체 인식](https://www.acmicpc.net/problem/22352)
+ *
+ * - 아이디어
+ * 영역 별 구분되어있는 모양이 같아야 함.
+ * 그리고 하나의 영역을 제외하고는 숫자가 같아야 함.
+ *
+ * - 트러블 슈팅
+ *
+ */
+class `전현수_항체_인식` {
+
+    private data class Position(val x: Int, val y: Int)
+
+    private val dirs = listOf(
+        Position(0, -1),
+        Position(-1, 0),
+        Position(0, 1),
+        Position(1, 0),
+    )
+
+    private val origin = mutableListOf<MutableList<Int>>()
+    private val expected = mutableListOf<MutableList<Int>>()
+
+    fun solution() {
+
+        val (n, m) = readln().split(" ").map { it.toInt() }
+
+        repeat(n) {
+            val row = readln().split(" ").map { it.toInt() }
+            origin.add(row as MutableList)
+        }
+
+        repeat(n) {
+            val row = readln().split(" ").map { it.toInt() }
+            expected.add(row as MutableList)
+        }
+
+        for (i in 0 until origin.size) {
+            for (j in 0 until origin.first().size) {
+
+                val curNumForOrigin = origin[i][j]
+                val curNumForExpected = expected[i][j]
+
+                if (curNumForOrigin != curNumForExpected) {
+
+                    val visited = Array(n) {
+                        BooleanArray(m)
+                    }
+
+                    dfs(curNumForOrigin, curNumForExpected, Position(i, j), origin, visited)
+
+                    if (origin.flatten() == expected.flatten()) println("YES")
+                    else println("NO")
+                    exitProcess(0)
+                }
+            }
+        }
+
+        println("YES")
+
+    }
+
+    private fun dfs(
+        targetNum: Int,
+        expectNumber: Int,
+        targetPos: Position,
+        target: MutableList<MutableList<Int>>,
+        visited: Array<BooleanArray>,
+    ) {
+
+        val curNum = target[targetPos.x][targetPos.y]
+
+        if (targetNum != curNum) return
+
+        visited[targetPos.x][targetPos.y] = true
+        target[targetPos.x][targetPos.y] = expectNumber
+
+        dirs.forEach { dir ->
+
+            val nx = targetPos.x + dir.x
+            val ny = targetPos.y + dir.y
+
+            if (nx !in 0 until target.size ||
+                ny !in 0 until target.first().size ||
+                visited[nx][ny]
+            ) return@forEach
+
+            dfs(targetNum, expectNumber, Position(nx, ny), target, visited)
+        }
+
+    }
+
+}
+
+fun main() {
+    전현수_항체_인식().solution()
+}
\ No newline at end of file