Relatives

题意是：找一个数比他小的互质数，用欧拉函数

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.

Input

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.

Output

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

Sample Input

7
12
0

Sample Output

6
4

代码：

#include <iostream>
using namespace std;
#include<stdio.h>
#include<string.h>
int d[100],k;
void f(int a)
{
    int i,flag;
    k=0;
    for(i=2;a!=1;i++)
    {
        flag=0;
        while(a%i==0)
        {
            flag=1;
            d[k]=i;
            a/=i;
        }
        if(flag)
            k++;
    }
}
int main()
{
    int n,i,s;
    while(scanf("%d",&n)!=EOF&&n!=0)
    {
        f(n);
        for(i=0;i<k;i++)
        {
            s=0;
            s+=(n-n/d[i]);
            n=s;
        }
        printf("%d\n",s);
    }
    return 0;
}