#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1e9 + 7;
const long long SIZE = 100000;
const int INF = 0x3f3f3f3f;
const long long ll_INF = 0x3f3f3f3f3f3f3f3f;
const long double PI = acos(-1);
const long long MAXN = numeric_limits<long long>::max();
const long long MAX = 2000000;
void disp(vector<long long> v) {
  for (auto u : v) cout << u << " ";
  cout << '\n';
}
void solve() {
  int n, x = 0, y = 1, temp = 0;
  cin >> n;
  long long k = 3 * n + 4;
  cout << k << '\n';
  cout << 0 << " " << 0 << '\n';
  cout << 1 << " " << 0 << '\n';
  for (long long i = 0; i < n; i++) {
    x = temp;
    for (long long i = 0; i < 3; i++) {
      cout << x << " " << y << '\n';
      x++;
    }
    y++;
    temp++;
  }
  x = temp;
  cout << x << " " << y << '\n';
  cout << x + 1 << " " << y << '\n';
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  solve();
  return 0;
}
