0 : {}
1 : {1,12,123}
2 : {2,21,23}
3 : {3,32,321}
4 : {13,132}
5 : {121,1213,12132}
6 : {213,2132}
7 : {232,2321,21321}
8 : {1232,1321,12321}
9 : {121321}