Preorder Traversal

Each input file contains one test case. For each case, the first line gives a positive integer N (≤ 50,000), the total number of nodes in the binary tree. The second line gives the postorder sequence and the third line gives the inorder sequence. All the numbers in a line are separated by a space.

For each test case, print in one line the last number of the preorder traversal sequence of the corresponding binary tree.