Poj 2407

水题，纯欧拉函数模板

#include <iostream>

#include <stdio.h>

using namespace std;

 

long long eu(long long n)

{

long long i,ret=1;

for(i=2;i*i<=n;i++)

if(n%i==0)

{

n/=i;

ret*=i-1;

while(n%i==0)

{

ret*=i;

n/=i;

}

}

if(n>1)

ret*=n-1;

return ret;

}

 

int main()

{

long long n;

//freopen("in.txt","r",stdin);

while(cin>>n)

{

if(n==0)

break;

else

cout<<eu(n)<<endl;

}

 

return 0;

}