#include <bits/stdc++.h>
using namespace std;
long long int minn(long long int a, long long int b) {
  if (a > b) return b;
  return a;
}
long long int maxx2(long long int a, long long int b) {
  if (a > b) return a;
  return b;
}
long long int maxx(long long int a, long long int b, long long int c) {
  return maxx2(a, maxx2(b, c));
}
long long int gcdd(long long int a, long long int b) {
  if (b == 0)
    return a;
  else
    return gcdd(b, a % b);
}
long long int dsum(long long int n) {
  long long int sum = 0;
  while (n > 0) {
    sum += n % 10;
    n /= 10;
  }
  return sum;
}
long long int poww(long long int a, long long int b) {
  if (b <= 0) return 1;
  if (b == 1) return a;
  if (b == 2)
    return (a * a);
  else
    return poww(poww(a, b / 2), 2) * (poww(a, b % 2));
}
long long int sumsq(long long int x, long long int y, long long int z) {
  return (x - y) * (x - y) + (y - z) * (y - z) + (z - x) * (z - x);
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  long long int n;
  cin >> n;
  cout << 3 * (n - 1) + 7 << endl;
  long long int x = 2, y = 2;
  cout << "0 0" << endl;
  cout << "0 1" << endl;
  cout << "1 0" << endl;
  cout << "1 1" << endl;
  cout << "1 2" << endl;
  cout << "2 1" << endl;
  for (long long int i = 1; i < n; i++) {
    cout << x << " " << y << endl;
    cout << x + 1 << " " << y << endl;
    cout << x << " " << y + 1 << endl;
    x++;
    y++;
  }
  cout << x << " " << y << endl;
  return 0;
}
