#include <bits/stdc++.h>
#define nmax 1000001
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int phi[nmax];
int main()
{
    int x,nr,n;
    fin>>n;
    for(int i=1;i<=n;i++)
        phi[i]=i-1;
    for(int i=2;i<=n;i++)
    {
        x=phi[i];
        for(int j=2*i;j<=n;j+=i)
        {
            phi[j]=phi[j]-x;

        }
        nr+=x;
    }
    fout<<2*nr+1;

    return 0;
}