#include <bits/stdc++.h>
using namespace std;
int main() {
  int t = 1;
  while (t--) {
    int n;
    cin >> n;
    cout << 3 * n + 4 << "\n";
    cout << 0 << " " << 0 << "\n";
    cout << 1 << " " << 0 << "\n";
    int x, y;
    x = 0;
    y = 1;
    while (y <= n) {
      for (int i = 0; i < 3; ++i) {
        cout << x + i << " " << y << "\n";
      }
      x++;
      y++;
    }
    cout << x + 0 << " " << y << "\n";
    cout << x + 1 << " " << y << "\n";
  }
  return 0;
}
