POJ 2047 Relatives 欧拉函数

#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<ctime>
#include<algorithm>
using namespace std;

#define lint __int64

lint Euler ( lint n )
{
lint i, ret = n;
for ( i = 2; i * i <= n; i++ )
{
if ( n % i == 0 )
{
n /= i;
ret = ret - ret / i;
while ( n % i == 0 )
n = n / i;
}
}
if ( n > 1 )
ret = ret - ret / n;
return ret;
}

int main()
{
lint n;
while ( scanf("%I64d",&n) && n )
printf("%I64d\n",Euler(n));
return 0;
}