#include <cstdio>

using namespace std;

const int Max = 1000001;

int phi[Max];

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

    int N, i, j;
    long long Sum = 0;

    scanf("%d", &N);
    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++) Sum += phi[i]*2;
    printf("%lld\n", Sum+1);
    return 0;
}