#include <fstream>
using namespace std;
ifstream in ("fractii.in");
ofstream out ("fractii.out");

long long n, i, j, cnt = 0, v [ 1000000 ];

int main()
{
    in>>n;

    for ( i = 2; i <= n; ++i )
    {
        v [ i ] += i - 1;
        for ( j = i + i; j <= n; j += i )
            v [ j ] -= v [ i ];
        cnt += v [ i ];
    }

    out<<2*cnt + 1;
    return 0;
}