#include <bits/stdc++.h>

using namespace std;

ifstream f("fractii.in");
ofstream g("fractii.out");

int N, sol, prime[1000003];
int main() {
   f >> N;
   for(int i = 1; i <= N; i++) {
      prime[i] = i - 1;
   }
   for(int i = 2; i <= N; i++) {
      if(prime[i]) {
         for(int j = 2 * i; j <= N; j += i)
            prime[j] -= prime[i];
         sol += prime[i];
      }
   }
   g << sol * 2 + 1 << "\n";
   return 0;
}