/*
	Relatively Prime
	@Author: md.moniruzzaman
*/
#include<stdio.h>

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

void main() {
	int n;
	scanf("%d",&n);
	printf("%d\n",countRelativelyPrime(n));
}