#include <stdio.h>
#define Nmax 1000001

long long n, i, j, S;
long long v[Nmax];

int main (){
	FILE * f = fopen ("fractii.in", "r");
	FILE * g = fopen ("fractii.out", "w");

	fscanf (f, "%lld", &n);
	
	for (i = 2 ; i <= n ; i++){
		v[i] += i-1;
		S = S + v[i];
		for (j = 2*i ; j <= n ; j++)
			v[j] -= v[i];
	}
	
	S = S*2 + 1;
	fprintf (g ,"%lld", S);

	fclose(f);
	fclose(g);
	return 0;
}