# import random failed def check if or return False if return False if r

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52``` ```import random failed = [ (2, 2), (3, 3), (2, 3), (3, 2), (2, 4), (4, 2) ] def check(u, v): if u[0] == v[0] or u[1] == v[1]: return False if u[0] - u[1] == v[0] - v[1]: return False if u[0] + u[1] == v[0] + v[1]: return False return True def process(d): for i in range(len(d)-1): if not check(d[i], d[i+1]): for j in range(i+2, len(d)): if check(d[i], d[j]): d[i+1], d[j] = d[j], d[i+1] break if not check(d[i], d[i+1]): return False return True t = int(input()) for test_num in range(1, t + 1): n, m = map(int, input().split(' ')) if (n, m) in failed: print("Case #{}: IMPOSSIBLE".format(test_num)) continue r = [(i+1, j+1) for i in range(n) for j in range(m)] while True: random.shuffle(r) if process(r): print("Case #{}: POSSIBLE".format(test_num)) for step in r: print('{} {}'.format(step[0], step[1])) break ```