POJ 2407 Relatives

#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
#include <cstdlib>
#include <iostream>
#include <algorithm>
#include <stack>
#include <map>
#include <set>
#include <vector>
#include <sstream>
#include <queue>
#include <utility>
using namespace std;

#define rep(i,j,k) for (int i=j;i<=k;i++)
#define Rrep(i,j,k) for (int i=j;i>=k;i--)

#define Clean(x,y) memset(x,y,sizeof(x))
#define LL long long
#define ULL unsigned long long
#define inf 0x7fffffff
#define mod %100000007

LL n;

LL cal( LL x )
{
LL ans = 1;

for( int i = 2; i*i <= x; i++ )
{
if ( x % i == 0)
{
ans*=i-1;
x /= i;
while( x % i == 0 )
{
ans *= i;
x /= i;
}
}
}
if ( x > 1 ) ans*=(x-1);
return ans;
}

int main()
{
while(cin>>n)
{
if ( !n ) break;
cout<<cal(n)<<endl;
}
return 0;
}