//#include <iostream>
#include <fstream>
using namespace std;
int n,rasp[1000005];
ifstream cin("fractii.in");
ofstream cout("fractii.out");
int main()
{
    cin>>n;
    for(int i=1;i<=n;i++){
        rasp[i]=i-1;
    }
    for(int i=2;i<=n;i++){
        for(int j=2*i;j<=n;j+=i){
            rasp[j]-=rasp[i];
        }
    }
    long long sum=0;
    for(int i=1;i<=n;i++){
        //cout<<rasp[i]<<" ";
        sum+=rasp[i];
    }
    cout<<sum*2+1;
    return 0;
}