题目描述

Suppose that all the keys in a binary tree are distinct positive integers. Given the postorder and inorder traversal sequences, you are supposed to output the last number of the preorder traversal sequence of the corresponding binary tree.

输入格式

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.