#include <fstream>

using namespace std;

ifstream fin ("fractii.in");
ofstream fout ("fractii.out");

int n,i,j,s,v[1000001];

int main()
{
    fin >> n;

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

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

    for ( i=1; i<=n; i++ )
        s += v[i];

    fout << 2 * s + 1;

    return 0;
}