#include<fstream>
#include<iostream>
using namespace std;
long long rez[1000003],sol,n,i,d;
int main()
{
    ifstream cin("fractii.in");
    ofstream cout("fractii.out");
    cin>>n;

    for(i=2;i<=n;i++)
        rez[i]=i-1;
    for(i=2;i<=n;i++)
    {
      
        for(int j=2*i;j<=n;j+=i)
            rez[j]-=rez[i];
        sol+=rez[i];
     }

    cout<<sol*2+1;
    return 0;
}