diff --git a/my_Tetris.py b/my_Tetris.py
index 0eef9fb..61b3f0e 100644
--- a/my_Tetris.py
+++ b/my_Tetris.py
@@ -54,7 +54,11 @@ def check(center):
         if cube[0] < 1 or cube[1] < 1 or cube[0] > grid_num_height \
                 or cube[1] >grid_num_width:
             return False
-
+        if num_list[cube[0]-1][cube[1]-1]!=0:
+            return False
+num_list=[]
+for i in range(25):
+    num_list.append([0]*15)
 while True:
     for event in pygame.event.get():
         if event.type == locals.QUIT: