#include <stdio.h>

int phi[1000000], N;

long long calc_phi(){
    long long sum = 0;
    for(int i = 1; i <= N; i++)
        phi[i] = i - 1;

    for(int i = 2; i <= N; i++){
        sum += phi[i];
        for(int j = 2*i; j <= N; j += i)
            phi[j] -= phi[i];
    }


    return sum;
}

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

    scanf("%d", &N);
    printf("%lld", (2 * calc_phi()) + 1);

    return 0;
}