diff --git a/src/fib.ts b/src/fib.ts
index 043f024..3d68b3e 100644
--- a/src/fib.ts
+++ b/src/fib.ts
@@ -1,15 +1,15 @@
+// src/fib.ts
+export function fibonacci(n: number): number {
+  if (n < 0) return -1;
+  if (n === 0) return 0;
+  if (n === 1) return 1;
 
-
-export default function fibonacci(n: number): number {
-    if (n < 0) return -1; // handle invalid input
-    if (n === 0) return 0;
-    if (n === 1) return 1;
-
-    let a = 0, b = 1;
-    for (let i = 2; i <= n; i++) {
-        const temp = a + b;
-        a = b;
-        b = temp;
-    }
-    return b;
-}
+  let a = 0;
+  let b = 1;
+  for (let i = 2; i <= n; i++) {
+    const next = a + b;
+    a = b;
+    b = next;
+  }
+  return b;
+}
\ No newline at end of file
diff --git a/src/fibRoute.ts b/src/fibRoute.ts
index 4855748..e29c157 100644
--- a/src/fibRoute.ts
+++ b/src/fibRoute.ts
@@ -1,3 +1,4 @@
+// src/fibRoute.ts
 import type { Request, Response } from "express";
 import { fibonacci } from "./fib";