#include <bits/stdc++.h>
using namespace std;
vector<pair<int, int>> res;
void printat(int x, int y) {
  for (int i = 0; i < 3; i++) {
    for (int j = 0; j < 3; j++) {
      if (i == 1 and j == 1) continue;
      if (i == 2 and j == 2) continue;
      res.push_back({x + i, y + j});
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  int n;
  cin >> n;
  int x = 0;
  int y = 0;
  for (int i = 0; i <= n; i++, x += 2, y += 2) {
    printat(x, y);
  }
  res.push_back({x, y});
  cout << res.size() << "\n";
  for (auto p : res) {
    cout << p.first << " " << p.second << "\n";
  }
  return 0;
}
