#include <stdio.h>

long a[1000010];
long i, j, n; 
long long s;

int main()
{
    freopen("fractii.in", "r", stdin);
    freopen("fractii.out", "w", stdout);
    scanf("%d\n", &n);
    for(i=2; i<=n; i++)
    {
        a[i]+=i-1;
        for(j=2; i*j<=n; j++)
        {
            a[i*j]-=a[i];
        }
        s+=a[i];
    }
    printf("%lld\n", s*2+1);
    return 0;
}