#include <bits/stdc++.h>
using namespace std;
const int N = 3e5 + 7;
const int M = 3e6 + 7;
const int MXN = 1e6 + 5;
const int MOD = 1e9 + 7;
const int INF = 0x3f3f3f3f;
int main() {
  int n, x = 1;
  cin >> n;
  cout << (3 * (n + 1)) + 1 << endl;
  ++n;
  for (int i = 0; i <= n; ++i) {
    if (i == 0) {
      cout << "0 0\n1 0\n";
      continue;
    }
    if (i == n) {
      cout << n - 1 << ' ' << n << endl << n << ' ' << n;
      break;
    }
    cout << x - 1 << ' ' << x << endl
         << x << ' ' << x << endl
         << x + 1 << ' ' << x << endl;
    ++x;
  }
  return 0;
}
