#include <iostream>
#include <fstream>
using namespace std;

int v[1000005];
int main()
{
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    int n,i,j;
    long long k=0;
    f>>n;
    for(i=2;i<=n;i++)
        v[i]=i-1;
    for(i=2;i<=n;i++){
        for(j=i+i;j<=n;j+=i)
            v[j]=v[j]-v[i];
        k+=v[i];
    }
    g<<2*k+1;

}