#include <bits/stdc++.h>
using namespace std;
template <typename T>
void PrArr(const T a[], int len) {
  for (int i = 0; i <= len; i++) cout << a[i] << " ";
  cout << endl;
}
template <typename T>
void PrVec(const vector<T> a) {
  for (auto it : a) cout << it << " ";
  cout << endl;
}
template <class T>
inline void read(T &res) {
  char c;
  T flag = 1;
  while ((c = getchar()) < '0' || c > '9')
    if (c == '-') flag = -1;
  res = c - '0';
  while ((c = getchar()) >= '0' && c <= '9') res = res * 10 + c - '0';
  res *= flag;
}
const int MAX = 0x7ffffff;
const int MIN = 0xcf;
int test;
void slove() {
  int n;
  cin >> n;
  cout << 4 + 3 * n << endl;
  cout << "0 0\n0 1\n";
  int t = n, row = 1, col = 0;
  while (t--) {
    for (int i = 0; i <= 2; i++) {
      cout << row << " " << col + i << endl;
    }
    row++, col++;
  }
  cout << row << " " << col + 0 << endl;
  cout << row << " " << col + 1 << endl;
}
int main() {
  std::ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  ;
  slove();
}
