OJ-Problems-Source/HDOJ/1787_autoAC.cpp

#include <stdio.h>  
using namespace std;  
#define N 100000001  
int euler(int n)  
{  
    int ans=1;  
    int i;  
    for(i=2;i*i<=n;i++)  
    {  
        if(n%i==0)  
        {  
            n/=i;  
            ans*=i-1;  
            while(n%i==0)  
            {  
                n/=i;  
                ans*=i;  
            }  
        }  
    }  
    if(n>1)  
        ans*=n-1;  
    return ans;  
}  
int main()  
{  
    int n;  
    while(scanf("%d",&n),n)  
    {  
        printf("%d\n",n-1-euler(n));  
    }  
    return 0;  
}