C :

#include<stdio.h>

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

int main()
{
	int n;
	while(scanf("%d",&n)!=EOF,n)
		printf("%d\n",eular(n));
	return 0;
}

C++ :

#include<stdio.h>

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

int main()
{
	int n;
	while(scanf("%d",&n)!=EOF,n)
		printf("%d\n",eular(n));
	return 0;
}

Java :

import java.util.Scanner;   
public class Main {   
 
static int eular(int n)
{
    int ret = 1,i;
    for (i = 2;i * i <= n;i++)
        if (n % i == 0)
        {
            n /= i;
            ret *= (i - 1);
            while (n % i == 0)
            {
                n /= i;
                ret *= i;
            }
        }
    if (n > 1)
        ret *= (n - 1);
    return ret;
}


 public static void main(String[] args) {   
    Scanner sc = new Scanner(System.in);   
   
    while(sc.hasNext()){
     int n=sc.nextInt();
     if(n==0) break;
     System.out.println(eular(n));
   }
  }
}