#include <fstream>
using namespace std;

int n, a[1000001], i, j;
long long nr;

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

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