#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
using namespace std;
long long int modularPower(long long int x, unsigned long long int y,
                           long long int mod) {
  long long int res = 1;
  x %= mod;
  while (y > 0) {
    if (y & 1) res = (res * x) % mod;
    y >>= 1;
    x = (x * x) % mod;
  }
  return res;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cerr.tie(NULL);
  cout.tie(NULL);
  ;
  int tests = 1;
  while (tests--) {
    int n;
    cin >> n;
    vector<pair<int, int> > v = {{1, 1}, {1, 0}, {0, 1}};
    cout << 3 * n + 4 << "\n0 0\n";
    for (int i = 0; i <= n; ++i)
      for (auto p : v) cout << i + p.first << " " << i + p.second << "\n";
  }
  return 0;
}
