#include <iostream>
#include <fstream>

using namespace std;


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

int n,i,j,v[1000005];
long long sum;
int main()
{
    f>>n;
    for(i=1;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++)
        sum+=v[i];
    g<<2*sum+1;

    return 0;
}