diff --git a/polygon.cpp b/polygon.cpp
index 6b87a7f75..bc2292e32 100644
--- a/polygon.cpp
+++ b/polygon.cpp
@@ -1,4 +1,7 @@
 #include <stdio.h>
+#include <algorithm>
+#include <set>
+#include <vector>
 #include "geometry.hpp"
 
 struct point {