题目描述

Problem E: Relatives

Given n, a positive integer, how many positive integers less than n are relatively prime to n? Two integers a and b are relatively prime if there are no integers x > 1, y > 0, z > 0 such that a = xy and b = xz.

There are several test cases. For each test case, standard input contains a line with n <= 1,000,000,000. A line containing 0 follows the last case.

For each test case there should be single line of output answering the question posed above.

样例 1

输入

7
12
0

输出

6
4

题目来源：fps-zhblue-waterloo-020601.xml；FPS 共享题包，题包内第 5 题。保留原作者与原赛事署名。