Case #1: 2
Case #2: 6
Case #3: 0
Case #4: 2
Case #5: 1
Case #6: IMPOSSIBLE
Case #7: 2
Case #8: 4
Case #9: 3
Case #10: 0
Case #11: 2
Case #12: 1
Case #13: IMPOSSIBLE
Case #14: IMPOSSIBLE
Case #15: 7
Case #16: 4
Case #17: 7
Case #18: 3
Case #19: IMPOSSIBLE
Case #20: IMPOSSIBLE