#include <stdio.h>
#define Nmax 1000001

int N, i, j, c[Nmax], rez;

int main()
{
	fscanf(fopen("fractii.in", "r"), "%d", &N);
	for (i = 1; i<=N; ++i) c[i] = i;
	for(i = 2; i <=N; ++i)
		if (c[i] == i)
		for (j = 1; i*j<=N; ++j)
			c[i*j] *= (i-1) / i;
	for (i = 2; i<=N; ++i) rez+=c[i];
	fprintf(fopen("fractii.out", "w"), "%d", 2*rez+1);
	return 0;
}