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