#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long n;
  cin >> n;
  long long x = 1000000, y = 1000000;
  vector<pair<long long, long long>> ans;
  ans.push_back({x, y});
  ans.push_back({x + 1, y});
  ans.push_back({x, y - 1});
  ans.push_back({x + 1, y - 1});
  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 x : ans) cout << x.first << " " << x.second << "\n";
}
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  solve();
  return 0;
}
