#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int p = n + 1;
  int cnt = 0;
  cout << ((n + 1) * 3) + 1 << endl;
  for (int i = 0; i < p; i++) {
    cout << i << ' ' << i << endl;
    cout << i + 1 << ' ' << i << endl;
    cout << i << ' ' << i + 1 << endl;
    cnt += 3;
  }
  cout << p << ' ' << p << endl;
}
