diff --git a/usaco/Do You Know Your ABCs?/index.cpp b/usaco/Do You Know Your ABCs?/index.cpp
index e6c2c9a..47fe76b 100644
--- a/usaco/Do You Know Your ABCs?/index.cpp	
+++ b/usaco/Do You Know Your ABCs?/index.cpp	
@@ -1,3 +1,4 @@
+#include <algorithm>
 #include <iostream>
 using namespace std;