#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define max 1000005

int array[max];

int main() {

    FILE* in = fopen("fractii.in", "r");
    FILE* out = fopen("fractii.out", "w");

    int n;
    fscanf(in, "%d", &n);

    int rezult = 0;

    for(int i=2;i<=n;i++)
        array[i]=i-1;

    for(int i=2;i<=n;i++) {

        rezult+=array[i];

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

    }

    fprintf(out, "%d", 1LL* 2*rezult + 1);

    return 0;

}