#include <cstdio>

using namespace std;
int n;
int ciur[1000001];
long long fractii =0;


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