diff --git a/app.js b/app.js
index ad9a93a7..4b3b8f37 100644
--- a/app.js
+++ b/app.js
@@ -1 +1,12 @@
 'use strict';
+const memo = new Map();
+memo.set(0, 0);
+memo.set(1, 1);
+function fib(n) {
+    if (memo.has(n)) {
+        return memo.get(n);
+      }
+      const value = fib(n - 1) + fib(n - 2);
+      memo.set(n, value);
+      return value;
+    }
\ No newline at end of file