#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int n;
  cin >> n;
  cout << 4 + 3 * n << endl;
  cout << 0 << " " << 0 << endl;
  long long int x = 0, y = 0;
  for (long long int i = 0; i <= n; i++) {
    cout << x << " " << y + 1 << endl;
    cout << x + 1 << " " << y << endl;
    cout << x + 1 << " " << y + 1 << endl;
    x++;
    y++;
  }
  return 0;
}
