Add clap argument parser

The program will accept 2 optional arguments, one to the select the
input folder, the other one to select for folder for the inputs.

Cargo.toml

@@ -4,3 +4,4 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+clap = { version = "4.5.21", features = ["derive"] }

src/main.rs

@@ -1,3 +1,16 @@
-fn main() {
-    println!("Hello, world!");
+use clap::Parser;
+
+#[derive(Parser, Debug)]
+#[command(version, about, long_about = None)]
+struct Args {
+    #[arg(short, long, default_value_t = String::from("input_examples"))]
+    input_folder: String,
+    #[arg(short, long, default_value_t = 1)]
+    day: u8,
 }
+
+fn main() {
+    let args = Args::parse();
+
+    println!("Running day {} with input folder <{}>!", args.day, args.input_folder);
+}