pos = [[0, -1], [0, -2], [0, -3], [1, -3], [2, -3], [3, -3], [3, -4], [3, -5], [4, -5], [5, -5], [5, -4], [5, -3], [6, -3], [7, -3], [7, -4], [7, -5], [7, -6], [7, -7], [6, -7], [5, -7], [4, -7], [3, -7], [2, -7], [1, -7], [0, -7], [-1, -7], [-1, -6], [-1, -5]]