#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC target("sse4")
using namespace std;
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n;
  cin >> n;
  cout << 3 * n + 4 << "\n";
  long long x = 1, y = 1;
  cout << x << " " << y << "\n";
  cout << x + 1 << " " << y << "\n";
  for (long long i = 1; i <= n; i++) {
    x++;
    y++;
    cout << x << " " << y << "\n";
    cout << x - 1 << " " << y << "\n";
    cout << x + 1 << " " << y << "\n";
  }
  x++;
  y++;
  cout << x << " " << y << "\n";
  cout << x - 1 << " " << y << "\n";
  return 0;
}
