#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  int n, x = 1, y = 1;
  cin >> n;
  vector<pair<int, int> > v;
  v.push_back({-1, 0});
  v.push_back({-1, -1});
  v.push_back({0, -1});
  v.push_back({0, 0});
  for (int i = 0; i < n; i++) {
    v.push_back({x, y});
    v.push_back({x - 1, y});
    v.push_back({x, y - 1});
    x++, y++;
  }
  cout << v.size() << '\n';
  for (int i = 0; i < v.size(); i++)
    cout << v[i].first << ' ' << v[i].second << '\n';
  return 0;
}
