1 files changed, 1 insertions, 1 deletions
diff --git a/util.h b/util.h
index e890555..52c37ae 100644
--- a/util.h
+++ b/util.h
@@ -10,7 +10,7 @@ using namespace std;
 
 
 struct Idx {
-	inline Idx(int idx) : x(idx % BSZ), y(idx / BSZ) {}
+	inline Idx(int idx) : x(idx % BSZ - BMID), y(idx / BSZ - BMID) {}
 
 	int x, y;
 };