#include <cstdio>

int v[1000005];

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