diff --git a/src/main.rs b/src/main.rs
index b17644a..fab1029 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -47,6 +47,9 @@ fn prepare_year(year: &str) -> Result<(), std::io::Error> {
 
 fn prepare_day(year: &str, day: &str) -> Result<(), std::io::Error> {
     let root = env!("CARGO_MANIFEST_DIR");
+    if Path::new(&format!("{root}/y{year}/src/bin/d{day}.rs")).exists() {
+        panic!("Day y{year}d{day} already exists")
+    }
     let bin = fs::read_to_string(format!("{root}/template/bin/d.rs.tmpl"))?
         .replace("{{YEAR}}", year)
         .replace("{{DAY}}", day);
diff --git a/y2015/resources/18_input.txt b/y2015/resources/18_input.txt
new file mode 100644
index 0000000..83f3cb2
--- /dev/null
+++ b/y2015/resources/18_input.txt
@@ -0,0 +1,100 @@
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diff --git a/y2015/src/bin/d15.rs b/y2015/src/bin/d15.rs
index e8df673..8d30aeb 100644
--- a/y2015/src/bin/d15.rs
+++ b/y2015/src/bin/d15.rs
@@ -16,5 +16,6 @@ fn part1() {
 fn part2() {
     let root = env!("CARGO_MANIFEST_DIR");
     let content = fs::read_to_string(format!("{root}/resources/15_input.txt")).unwrap();
-    println!("{}", d15::process_part2(&content));
+    // change comments in part1
+    //println!("{}", d15::process_part2(&content));
 }
diff --git a/y2015/src/bin/d18.rs b/y2015/src/bin/d18.rs
new file mode 100644
index 0000000..fb3f4d5
--- /dev/null
+++ b/y2015/src/bin/d18.rs
@@ -0,0 +1,20 @@
+use std::fs;
+
+use y2015::days::d18;
+
+fn main() {
+    part1();
+    part2();
+}
+
+fn part1() {
+    let root = env!("CARGO_MANIFEST_DIR");
+    let content = fs::read_to_string(format!("{root}/resources/18_input.txt")).unwrap();
+    println!("{}", d18::process_part1(&content));
+}
+
+fn part2() {
+    let root = env!("CARGO_MANIFEST_DIR");
+    let content = fs::read_to_string(format!("{root}/resources/18_input.txt")).unwrap();
+    println!("{}", d18::process_part2(&content));
+}
diff --git a/y2015/src/days/d15.rs b/y2015/src/days/d15.rs
index 565568b..5916d1d 100644
--- a/y2015/src/days/d15.rs
+++ b/y2015/src/days/d15.rs
@@ -185,10 +185,4 @@ Cinnamon: capacity 2, durability 3, flavor -2, texture -1, calories 3";
         let result = process_part1(INPUT);
         assert_eq!(result, 62842880);
     }
-
-    #[test]
-    fn part2() {
-        let result = process_part2(INPUT);
-        assert_eq!(result, 0);
-    }
 }
diff --git a/y2015/src/days/d18.rs b/y2015/src/days/d18.rs
new file mode 100644
index 0000000..9025dcc
--- /dev/null
+++ b/y2015/src/days/d18.rs
@@ -0,0 +1,26 @@
+pub fn process_part1(input: &str) -> i32 {
+    0
+}
+
+pub fn process_part2(input: &str) -> i32 {
+    0
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const INPUT: &str = "{{EXAMPLE}}";
+
+    #[test]
+    fn part1() {
+        let result = process_part1(INPUT);
+        assert_eq!(result, 0);
+    }
+
+    #[test]
+    fn part2() {
+        let result = process_part2(INPUT);
+        assert_eq!(result, 0);
+    }
+}
diff --git a/y2015/src/days/mod.rs b/y2015/src/days/mod.rs
index 7e6bd80..0e75767 100644
--- a/y2015/src/days/mod.rs
+++ b/y2015/src/days/mod.rs
@@ -17,3 +17,9 @@ pub mod d9;
 pub mod d16;
 
 pub mod d17;
+
+pub mod d18;
+
+pub mod d18;
+
+pub mod d18;