#include <stdio.h>
unsigned int n, i, j;
long s;
FILE *f, *g;
int main()
{
    f = fopen("fractii.in", "r");
    g = fopen("fractii.out", "w");
    fscanf(f, "%d", &n);
    int v[n];
    for(i = 1; i <= n; i++)
        v[i] = i - 1;
    for(i = 2; i <= n; i++) //ciurul lui eratostene
        for(j = i + i; j <= n; j += i)
            v[j] -= v[i];
    for(i = 2; i <= n; i++)
        s += v[i];
    fprintf(g, "%ld", s+s+1);
    fclose(f); fclose(g);
    return 0;
}