diff --git a/README.md b/README.md
index 5bc74c5..d744b12 100644
--- a/README.md
+++ b/README.md
@@ -254,7 +254,6 @@ java -jar czechtina.jar build/ukol.cz --no-compile --fpeterek --friendly --set-d
 
 ## TODO
 
-- invalidate "1 je 3"
 - std lib
 - string anotation
 - better cli
@@ -262,6 +261,7 @@ java -jar czechtina.jar build/ukol.cz --no-compile --fpeterek --friendly --set-d
 - rest of loop features.
 - structures
 - range definition
+- check validation of return type
 
 ## Credits
 
diff --git a/src/main/kotlin/AST/ASTFunctionCallNode.kt b/src/main/kotlin/AST/ASTFunctionCallNode.kt
index fee14f1..a360122 100644
--- a/src/main/kotlin/AST/ASTFunctionCallNode.kt
+++ b/src/main/kotlin/AST/ASTFunctionCallNode.kt
@@ -29,8 +29,9 @@ class ASTFunctionCallNode : ASTVariableNode {
                 return (params!! as ASTVariableNode).getType().toDynamic()
             if (function.toC() == "const")
                 return (params!! as ASTVariableNode).getType().toConst()
-            if (Compiler.definedFunctions[function.toC()]!!.validateParams(paramsTypes) != -1)
-                return Compiler.definedFunctions[function.toC()]!!.returnType
+            val variantIndex = Compiler.definedFunctions[function.toC()]!!.validateParams(paramsTypes)
+            if (variantIndex != -1)
+                return Compiler.definedFunctions[function.toC()]!!.getReturnType(variantIndex)
         }
         return DefinedType("none")
     }
diff --git a/src/main/kotlin/AST/ASTFunctionNode.kt b/src/main/kotlin/AST/ASTFunctionNode.kt
index cb188da..7dfe5f0 100644
--- a/src/main/kotlin/AST/ASTFunctionNode.kt
+++ b/src/main/kotlin/AST/ASTFunctionNode.kt
@@ -61,11 +61,11 @@ class ASTFunctionNode : ASTNode {
 
         if (Compiler.definedFunctions.containsKey(name!!)) {
             val newName = "${name}_v${Compiler.definedFunctions[name!!]!!.variants.size}"
-            Compiler.definedFunctions[name!!]!!.variants.add(compiler.DefinedFunctionVariant(newName, paramsTypes))
+            Compiler.definedFunctions[name!!]!!.variants.add(compiler.DefinedFunctionVariant(newName, paramsTypes, returnType = type.getType()))
             name = newName;
         }
         else
-            Compiler.definedFunctions += mapOf(name!! to compiler.DefinedFunction(name!!, compiler.DefinedType(type.toC()), listOf(compiler.DefinedFunctionVariant(name!!, paramsTypes)), virtual = false))
+            Compiler.definedFunctions += mapOf(name!! to compiler.DefinedFunction(name!!, type.getType(), listOf(compiler.DefinedFunctionVariant(name!!, paramsTypes, returnType = type.getType())), virtual = false))
         if (paramsTypes.any{it.isTemplate()})
             return "//${name}_Declaration_CZECHTINA ANCHOR\n"
 
diff --git a/src/main/kotlin/AST/ASTOperandNode.kt b/src/main/kotlin/AST/ASTOperandNode.kt
index 95dcdb7..83c79a3 100644
--- a/src/main/kotlin/AST/ASTOperandNode.kt
+++ b/src/main/kotlin/AST/ASTOperandNode.kt
@@ -29,7 +29,8 @@ class ASTOperandNode : ASTTypedNode {
         return ASTOperandNode(operand, left.copy(), right.copy())
     }
 
-    override fun toC(): String = when (operand) {
-        else -> "${left?.toC()} ${Compiler.typeFromCzechtina(operand)} ${right?.toC()}"
+    override fun toC(): String {
+        expType = Compiler.calcBinaryType(left, right, operand)
+        return "${left?.toC()} ${Compiler.typeFromCzechtina(operand)} ${right?.toC()}"
     }
 }
\ No newline at end of file
diff --git a/src/main/kotlin/AST/ASTUnaryNode.kt b/src/main/kotlin/AST/ASTUnaryNode.kt
index d8dcb58..5463fde 100644
--- a/src/main/kotlin/AST/ASTUnaryNode.kt
+++ b/src/main/kotlin/AST/ASTUnaryNode.kt
@@ -58,7 +58,7 @@ class ASTUnaryNode : ASTTypedNode {
     override fun toC(): String = when (type) {
         ASTUnaryTypes.LITERAL -> data.toString()
         ASTUnaryTypes.VARIABLE -> data.toString()
-        ASTUnaryTypes.TYPE -> if (getType().isTemplate()) getType().typeString else Compiler.typeFromCzechtina(data.toString())
+        ASTUnaryTypes.TYPE -> if (getType().isTemplate()) getType().typeString else getType().toC()
         ASTUnaryTypes.TYPE_POINTER -> "${(data as ASTNode).toC()}*"
         ASTUnaryTypes.RETURN -> "${Compiler.grammar[GrammarToken.KEYWORD_RETURN]} ${(data as ASTNode).toC()}"
         ASTUnaryTypes.IMPORT -> "//xd ${data.toString()}"
diff --git a/src/main/kotlin/compiler/Compiler.kt b/src/main/kotlin/compiler/Compiler.kt
index e1da430..6ff2105 100644
--- a/src/main/kotlin/compiler/Compiler.kt
+++ b/src/main/kotlin/compiler/Compiler.kt
@@ -1,9 +1,6 @@
 package compiler
 
-import AST.ASTListNode
-import AST.ASTNode
-import AST.ASTProgramNode
-import AST.ASTTypedNode
+import AST.*
 import cz.j_jzk.klang.input.InputFactory
 import czechtina.*
 import czechtina.header.createCzechtinaDefineFile
@@ -120,6 +117,8 @@ object Compiler {
         if (operand == "=") {
             if (left.getType().isConst && isParsed)
                 throw Exception("Cannot change const type of variable ${left}")
+            if (left is ASTVariableNode)
+                left.addType(right.getType())
             return DefinedType(right.getType())
         }
 
@@ -179,7 +178,6 @@ object Compiler {
         var cCode = tree.toC()
 
 
-
         while (isAnyUsedFunctionUndefined()) {
             for (function in definedFunctions){
                 val fce = function.value
diff --git a/src/main/kotlin/compiler/DefinedFunction.kt b/src/main/kotlin/compiler/DefinedFunction.kt
index f4c49cf..92b9e27 100644
--- a/src/main/kotlin/compiler/DefinedFunction.kt
+++ b/src/main/kotlin/compiler/DefinedFunction.kt
@@ -7,6 +7,10 @@ class DefinedFunction(val name: String,val returnType: DefinedType, val virtual:
         this.variants.addAll(variants)
     }
 
+    fun getReturnType(variantIndex : Int): DefinedType {
+        return variants[variantIndex].returnType ?: returnType
+    }
+
     fun validateParams(params: List<DefinedType>): Int {
         for (variant in variants) {
             if (variant.params.size != params.size){
@@ -59,7 +63,7 @@ class DefinedFunction(val name: String,val returnType: DefinedType, val virtual:
     override fun toString(): String = "\n$name: $returnType $virtual (\n\t${variants.joinToString("\n\t")}\n)"
 }
 
-class DefinedFunctionVariant(val translatedName: String, val params: List<DefinedType>, var defined:Boolean = true, val enableArgs: Boolean = false, val virtual: Boolean = false) {
+class DefinedFunctionVariant(val translatedName: String, val params: List<DefinedType>, val returnType: DefinedType? = null, var defined:Boolean = true, val enableArgs: Boolean = false, val virtual: Boolean = false) {
     var timeUsed: Int = 0
 
     override fun toString(): String = "$translatedName(${params.joinToString(",")}): $timeUsed $defined"
diff --git a/src/main/kotlin/compiler/DefinedType.kt b/src/main/kotlin/compiler/DefinedType.kt
index c88800d..7658516 100644
--- a/src/main/kotlin/compiler/DefinedType.kt
+++ b/src/main/kotlin/compiler/DefinedType.kt
@@ -18,6 +18,12 @@ class DefinedType {
         this.isConst = DT.isConst
     }
 
+    fun toC(): String {
+        if (isPointer() || isDynamic())
+            return "${getPrimitive()} *"
+        return getPrimitive()
+    }
+
     fun toHeap(): DefinedType {
         return DefinedType(typeString, true)
     }
@@ -55,6 +61,14 @@ class DefinedType {
         return typeString
     }
 
+    fun getPrimitive(): String {
+        if (isTemplate())
+            return getTemplate()
+        if (typeString.contains("-"))
+            return typeString.split("-")[1]
+        return typeString
+    }
+
 
     override fun toString(): String = "$typeString - $isHeap - $isConst"
 }
\ No newline at end of file
diff --git a/src/main/kotlin/czechtina/lesana/function.kt b/src/main/kotlin/czechtina/lesana/function.kt
index 1572761..0d64395 100644
--- a/src/main/kotlin/czechtina/lesana/function.kt
+++ b/src/main/kotlin/czechtina/lesana/function.kt
@@ -23,7 +23,7 @@ fun LesanaBuilder<ASTNode>.inlineFunction(
     )
     { (funName, varDef, _, line) ->
         ASTFunctionNode(
-            ASTUnaryNode(ASTUnaryTypes.TYPE, line.getType()),
+            ASTUnaryNode(ASTUnaryTypes.TYPE,data="", expressionType =  line.getType()),
             funName,
             listOf(varDef),
             ASTUnaryNode(
@@ -41,7 +41,7 @@ fun LesanaBuilder<ASTNode>.inlineFunction(
     )
     { (funName, varDefs, _, line) ->
         ASTFunctionNode(
-            ASTUnaryNode(ASTUnaryTypes.TYPE, line.getType()),
+            ASTUnaryNode(ASTUnaryTypes.TYPE,data="", expressionType =  line.getType()),
             funName,
             varDefs.nodes,
             ASTUnaryNode(
@@ -59,7 +59,7 @@ fun LesanaBuilder<ASTNode>.inlineFunction(
     )
     { (funName, _, line) ->
         ASTFunctionNode(
-            ASTUnaryNode(ASTUnaryTypes.TYPE, line.getType()),
+            ASTUnaryNode(ASTUnaryTypes.TYPE,data="", expressionType =  line.getType()),
             funName,
             listOf(),
             ASTUnaryNode(
diff --git a/src/main/kotlin/czechtina/regex.kt b/src/main/kotlin/czechtina/regex.kt
index 3a1c909..f977dcc 100644
--- a/src/main/kotlin/czechtina/regex.kt
+++ b/src/main/kotlin/czechtina/regex.kt
@@ -183,7 +183,7 @@ fun cTypeFromCzechtina (czechType: String): String {
         if (czechType == cValue)
             return cValue
     }
-    return ""
+    throw Exception("Unknown type $czechType")
 }
 
 
@@ -199,7 +199,7 @@ fun czTypeFromCzechtina (czechType: String): String {
         if (czechType == cValue)
             return cValue
     }
-    return ""
+    throw Exception("Unknown type $czechType")
 }
 
 fun cAndCzechtinaRegex (list: List<GrammarToken>): String = list.joinToString("|") { czechtina[it]!! + "|" + C[it]!! }