diff --git a/A.optimal_currency_exchange.cpp b/A.optimal_currency_exchange.cpp
index 8afcaf8..4a7c645 100644
--- a/A.optimal_currency_exchange.cpp
+++ b/A.optimal_currency_exchange.cpp
@@ -3,6 +3,7 @@
 #include <queue>
 #include <stack>
 #include <algorithm>
+#include <bits/stdc++.h>
 #include <math.h>
 #include <string>
 #include <cstring>
@@ -42,4 +43,4 @@ int main()
 	printf("%lld\n", mn);
 
 	return 0;
-}
\ No newline at end of file
+}