Given a tree, you are supposed to list all the leaves in the order of top down, and left to right.

Each input file contains one test case. For each case, the first line gives a positive integer N (≤10) which is the total number of nodes in the tree -- and hence the nodes are numbered from 0 to N−1. Then N lines follow, each corresponds to a node, and gives the indices of the left and right children of the node. If the child does not exist, a

For each test case, print in one line all the leaves

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