#include <bits/stdc++.h>
using namespace std;
int __ = 1;
void place(int a) {
  cout << a << " " << a << '\n';
  cout << a + 1 << " " << a << '\n';
  cout << a << " " << a + 1 << '\n';
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  for (int _ = 1; _ <= __; _++) {
    int n;
    cin >> n;
    int cnt = 0;
    cnt += 3 * (n + 1);
    cnt += 1;
    cout << cnt << '\n';
    place(0);
    for (int i = 1; i <= n; i++) {
      place(i);
    }
    cout << n + 1 << " " << n + 1 << '\n';
  }
  return 0;
}
