{2: 1, 18: 1}
{2: 2, 18: 2, 1: 2, 19: 1}
8 18
{2: 2, 18: 2, 1: 2, 19: 1, 7: 3, 8: 3}
5 7
{2: 2, 18: 2, 1: 2, 19: 1, 7: 3, 8: 3, 3: 3, 5: 3}
{2: 2, 18: 3, 1: 2, 19: 2, 7: 3, 8: 3, 3: 3, 5: 3, 17: 4, 20: 1}
4