#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f;
const long long inf = 0x3f3f3f3f3f3f3f3f;
const long long mod = 1e9 + 7;
const int N = 2e5 + 10;
int n;
int main() {
  scanf("%d", &n);
  printf("%d\n", 3 * n + 4);
  int x = 0, y = 0;
  for (int i = 0; i <= n + 1; i++) printf("%d %d\n", x + i, y + i);
  y++;
  for (int i = 0; i <= n; i++) printf("%d %d\n", x + i, y + i);
  y--;
  x++;
  for (int i = 0; i <= n; i++) printf("%d %d\n", x + i, y + i);
  return 0;
}
