#include <cstdio>

int v[1000005];

int main(){
	
	freopen("fractii.in", "r", stdin);
	freopen("fractii.out", "w", stdout);
	
	unsigned long long n;
	
	scanf("%d", &n);
	
	for(unsigned long long i = 1; i <= n; ++ i)
		v[i] = i - 1;
	
	unsigned long long rez = 0;
	
	for(unsigned long long i = 2; i <= n; ++ i){
		rez += v[i];
		for(unsigned long long  j = i + i; j <= n; j += i)
			v[j] -= v[i];
	}
	
	printf("%lld", 2 * rez + 1);
	
	return 0;
}