#include <cstdio>

using namespace std;

const int NMAX = 1000005;
long long phi[NMAX];

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