Phi

#include <stdio.h>
int gcd(int a,int b){
	if(a%b==0) return b;
	else gcd(b,a%b);
}

int main(){
	int n,i,count=0;
	scanf("%d",&n);

	for(i=1;i<=n;i++){
		if(gcd(i,n)==1) count++;
	}
	printf("Phi(%d ) = %d\n",n, count);

	return 0;
}