#include <bits/stdc++.h>
using namespace std;
string codeforces = "codeforces";
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long t, n, m, x, i, j, k, q;
  t = 1;
  while (t--) {
    cin >> n;
    vector<pair<int, int>> ans;
    int x = 5000, y = 5000;
    ans.push_back({x, y + 1});
    ans.push_back({x - 1, y});
    ans.push_back({x - 1, y + 1});
    ans.push_back({x, y});
    while (n--) {
      ans.push_back({x + 1, y});
      ans.push_back({x, y - 1});
      ans.push_back({x + 1, y - 1});
      x++;
      y--;
    }
    cout << ans.size() << '\n';
    for (auto& p : ans) cout << p.first << ' ' << p.second << '\n';
  }
}
