#include <stdio.h>

int main()
{
	freopen ("fractii.in","r",stdin);
	freopen ("fractii.out","w",stdout);

	int N, i, j;
	scanf("%d", &N);
	int phi[N + 1];
	int count = 0;
	for (i = 1; i <= N; ++i)
    	phi[i] = i-1;
	for (i = 2; i <= N; ++i)
    	for (j = 2*i; j <= N; j += i)
        	phi[j] -= phi[i];

    for(i = 1; i <= N; i++){
    	count += phi[i];
    }
	printf("%d\n", count * 2 + 1);
	return 0;
}