#include <iostream>
#include <fstream>

using namespace std;

const int Max = 1000005;
int phi[Max];
long long ans;
void Solve(int k){
for (int i = 1; i <= k; ++i)
    phi[i] = i-1;
for (int i = 2; i <= k; ++i){
    for (int j = 2*i; j <= k; j += i)
        phi[j] -= phi[i];
    ans += (1LL * 2 * phi[i]);
    }
}

int main(){
   int n;
   ifstream fin("fractii.in");
   ofstream fout("fractii.out");
   fin >> n;
   fin.close();
   Solve(n);
   fout << ++ans;
   fout.close();
   return 0;
}