#include <fstream>
#define N 10000001
using namespace std;
int s=0,v[N],n;
ofstream o("fractii.out");

int main()
{
    ifstream f("fractii.in");
    f>>n;
    for(int i=1;i<=n;i++)
        v[i]=i-1;
    for(int i=1;i<=n;i++){
        s = v[i]*2*1LL + s;

    for(int j=2*i;j<=n;j+=i)
        v[j]-=v[i];
    }
    o << ++s;
    return 0;
}