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


int n;
int array[NMAX];

int64_t fractions(){

    int i, j;
    int64_t sum = 0;

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

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


    return 2 * sum + 1;
}

int main()
{

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

    scanf("%d", &n);

    printf("%lld" , fractions());

    return 0;
}