#include <fstream>
using namespace std;

ifstream f("fractii.in");
ofstream g("fractii.out");

long long k;
int n, v[1000002];

int main()
{
    f>>n;
    for(int i=1;i<=n;++i) v[i]=i-1;
    for(int i=2;i<=n;++i)
    {
        k+=v[i];
        for(int j=i*2;j<=n;j+=i) v[j]-=v[i];
    }
    g<<k*2+1;
    return 0;
}