#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#define NMAX 2000015


int n, fr = 1;
int array[NMAX];

int fractions(){

    int i, j, sum = 0;

    for(i = 1; i <= n; ++i)
        array[i] = i - 1;

    for(i = 2; i <= n; ++i){
        for(j = i + i; j <= n; j += i)
            array[j] -= array[i];
        sum += array[i];
    }

    sum = 2 * sum + 1;

    return sum;
}

int main()
{

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

    scanf("%d", &n);

    printf("%d\n", fractions());

    return 0;
}