{3: 1, 12: 1}
11 12
{3: 2, 12: 1, 2: 2, 11: 2}
{3: 2, 12: 2, 2: 2, 11: 2, 15: 1}
{3: 2, 12: 2, 2: 2, 11: 2, 15: 1, 17: 1, 18: 1}
9 11
{3: 2, 12: 2, 2: 2, 11: 2, 15: 1, 17: 1, 18: 1, 6: 3, 9: 3}
3