dx, dy = (0, 0, 1, -1), (1, -1, 0, 0)
for i in range(row):
for j in range(col):
if matrix[i][j] == "*":
continue
count = 0
for k in range(4):
y, x = i + dy[k], j + dx[k]
if y in (-1, row) or x in (-1, col):
continue
if matrix[y][x] == "*":
count += 1
matrix[i][j] = count