#include <cstdio>
#include <vector>
#include <cmath>

int main(void)
{
    freopen("fractii.in", "r", stdin);
    freopen("fractii.out", "w", stdout);
    int nV;
    long long unsigned nC = 0;
    scanf("%d", &nV);
    int *nArr = new int[nV + 1];
    for(int i(1); i <= nV; i++)
    	nArr[i] = i - 1;
    for(int i(2); i <= nV; i++)
    {
		nC += nArr[i];
    	for(int j(i * 2); j <= nV; j += i)
    		nArr[j] -= nArr[i];  
    }
    printf("%llu",  2 * nC + 1);
    return 0;
}