#include <bits/stdc++.h>
using namespace std;
const int sz = 1e5 + 9, inf = INT_MAX;
void solve() {
  int n, m, k, l, r, x, y, ans, a, b;
  cin >> n;
  cout << 4 + (n * 3) << "\n";
  ;
  x = 0, y = 0;
  cout << x << " " << y << "\n";
  ;
  for (int i = 0; i <= n; i++) {
    cout << x + 1 << " " << y << "\n";
    ;
    cout << x << " " << y + 1 << "\n";
    ;
    cout << x + 1 << " " << y + 1 << "\n";
    ;
    x++, y++;
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int t = 1;
  while (t--) solve();
}
