#include <bits/stdc++.h>
using namespace std;
const int manx = 1e5 + 5;
const int N = 1e6 + 5;
const int mod = 1e9 + 7;
const int mo = 1e8;
int n, flag;
int main() {
  scanf("%d", &n);
  if (n % 2 == 1) {
    n--;
    flag = 1;
  }
  if (flag)
    cout << 6 * n + 15 << "\n";
  else
    cout << 6 * n + 12 << "\n";
  for (int i = 0; i < 2 * n + 4; i++) printf("1 %d\n", i);
  printf("2 0\n");
  printf("3 0\n");
  printf("2 %d\n", 2 * n + 3);
  printf("3 %d\n", 2 * n + 3);
  for (int i = 0; i < 2 * n + 4; i++) printf("4 %d\n", i);
  for (int i = 1; i <= n; i += 2) {
    printf("0 %d\n", i * 2);
    printf("0 %d\n", i * 2 + 1);
    printf("2 %d\n", i * 2);
    printf("2 %d\n", i * 2 + 1);
  }
  if (flag) {
    printf("0 %d\n", 2 * n + 3);
    printf("0 %d\n", 2 * n + 4);
    printf("1 %d\n", 2 * n + 4);
  }
  return 0;
}
