diff --git a/index.js b/index.js
index c423e11..42c15a3 100644
--- a/index.js
+++ b/index.js
@@ -1,6 +1,27 @@
 import { cc } from "bun:ffi";
 import source from "./test.c" with { type: "file" };
 
+
+function fibonacci_js() {
+    const n = 500000;
+    let a = 0n;
+    let b = 1n;
+    let c;
+
+    for (let i = 2; i <= n; i++) {
+        c = a + b;
+        a = b;
+        b = c;
+    }
+
+    return b;
+}
+
+const result_js = fibonacci_js();
+console.log("Fibonacci(500000) =", result_js.toString());
+
+
+
 const {
   symbols: { fibonacci },
 } = cc({