0
{3: 1, 9: 1}
{3: 1, 9: 2, 7: 1, 20: 1}
{3: 1, 9: 2, 7: 1, 20: 1, 15: 1}
{3: 1, 9: 3, 7: 2, 20: 1, 15: 2, 19: 1}
{3: 2, 9: 3, 7: 2, 20: 1, 15: 2, 19: 1, 1: 1, 5: 1}
3