1 files changed, 6 insertions, 0 deletions
diff --git a/XY.h b/XY.h
index 839e19f..8809104 100644
--- a/XY.h
+++ b/XY.h
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <functional>
+
 struct XY {
 	int x = 0;
 	int y = 0;
@@ -13,3 +15,7 @@ struct XY {
 	bool operator != (const XY& other) const;
 };
 
+template<> struct std::hash<XY> {
+	size_t operator () (const XY &) const;
+};
+