1 files changed, 6 insertions, 5 deletions
diff --git a/cses/IntroductoryProblems/BitStrings/main.cpp b/cses/IntroductoryProblems/BitStrings/main.cpp
index cb4a7fb..480a9ae 100755
--- a/cses/IntroductoryProblems/BitStrings/main.cpp
+++ b/cses/IntroductoryProblems/BitStrings/main.cpp
@@ -1,16 +1,17 @@
-#include<bits/stdc++.h>
+#include <bits/stdc++.h>
 
 using namespace std;
 
-int main () {
+int main() {
   ios_base::sync_with_stdio(false);
   cin.tie(NULL);
   int n;
   int m = 1e9 + 7;
   cin >> n;
-  long long ans = 0;
-  while(n--) {
-    ans += ((2 % m) * (2 % m)) % m;
+  n--;
+  long long ans = 2;
+  while (n--) {
+    ans = ((ans % m) * 2) % m;
   }
   cout << ans << '\n';
 }