#include <bits/stdc++.h> 
#define int long long

using namespace std;

ifstream fin( "fractii.in" );
ofstream fout( "fractii.out" );

const int NMAX = 1e6;
int phi[NMAX + 2];

signed main() {
  int n, i, j, sum;
  
  fin >> n;
  for( i = 1; i <= n; ++i ) 
    phi[i] = i;
  for( i = 1; 2 * i <= n; ++i ) 
    for( j = 2 * i; j <= n; j += i ) 
      phi[j] -= phi[i];
  
  sum = 0;
  for( i = 1; i <= n; ++i ) 
    sum += phi[i];
  fout << (sum - 1) * 2 + 1;
  return 0;
}