HDU 1953

#include<stdio.h>#include<math.h>long long int euler(long long int n){long long int i,m = (int)sqrt(n+0.5),ans = n;for(i = 2;i <= m;i++){if(n%i==0)ans = ans*(i-1)/i;while(n%i==0)n/=i;}if(n>1)ans = ans*(n-1)/n;return ans;}long long int a;int main(){while(scanf("%lld",&a)!=-1&&a!=0){printf("%lld\n",euler(a));}return 0;}