#include <bits/stdc++.h>
int main() {
  int n, x, y;
  scanf("%d", &n);
  printf("%d\n", 7 + 3 * (n - 1));
  printf("%d 0\n%d 0\n", n + 1, n);
  x = n + 1;
  for (y = 1; y <= n; y++) {
    printf("%d %d\n%d %d\n%d %d\n", x, y, x - 1, y, x - 2, y);
    x--;
  }
  printf("1 %d\n0 %d", y, y);
  return 0;
}
