#include <stdio.h>
#include <stdlib.h>

int phi[1000001];
int main() {
  FILE *fin, *fout;
  int n, i, j;
  long long s;
  fin = fopen( "fractii.in", "r" );
  fscanf( fin, "%d", &n );
  fclose( fin );
  // n = suma de phi(d), pentru oricare d | n
  // => phi(n) =  n - suma de phi(d), d | n, d < n
  for ( i = 1; i <= n; i++ )
    phi[i] = i - 1;
  s = 0;
  for ( i = 2; i <= n / 2; i++ ) {
    for ( j = 2 * i; j <= n; j+=i )
      phi[j] -= phi[i];
    s += phi[i];
  }
  fout = fopen( "fractii.out", "w" );
  fprintf( fout, "%lld", 2 * s + 1 );
  fclose( fout );
  return 0;
}