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#include <bits/stdc++.h>
#include <math.h>
using namespace std;
#define endl "\n"
#define mp make_pair
#define st first
#define nd second
#define pii pair<int, int>
#define pb push_back
#define _upgrade ios_base::sync_with_stdio(0), cout.setf(ios::fixed), cout.precision(10), cin.tie(0), cout.tie(0);
#define REP(i, n) for (int i = 0; i < (n); ++i)
#define FWD(i, a, b) for (int i = (a); i < (b); ++i)
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define fwd(i, a, b) for (int i = (a); i < (b); ++i)
#define all(c) (c).begin(), (c).end()
#define sz(X) (int)((X).size())
#define what(x) cerr << #x << " is " << x << endl;
#define int long long

ostream &operator<<(ostream &out, string str) {
   for (char c : str)
      out << c;
   return out;
}
template <class L, class R> ostream &operator<<(ostream &out, pair<L, R> p) { return out << "(" << p.st << ", " << p.nd << ")"; }
template <class T> auto operator<<(ostream &out, T a) -> decltype(a.begin(), out) {
   out << '{';
   for (auto it = a.begin(); it != a.end(); it = next(it))
      out << (it != a.begin() ? ", " : "") << *it;
   return out << '}';
}
void dump() { cerr << "\n"; }
template <class T, class... Ts> void dump(T a, Ts... x) {
   cerr << a << ", ";
   dump(x...);
}
#define debug(...) cerr << "[" #__VA_ARGS__ "]: ", dump(__VA_ARGS__)

const int MAXM = 200;

vector<int> tab[MAXM + 10];

void wypisz(vector<int> X) { cout << (X.size() >= 1 ? X[0] : -1) << " " << (X.size() >= 2 ? X[1] : -1) << endl; }

int32_t main() {
   _upgrade;
   tab[1].push_back(2);
   tab[1].push_back(3);
   int N = 100;

   int k;
   cin >> k;

   int cur = 1;
   while (k > 0) {
      tab[cur * 3 - 1].push_back(cur * 3 + 1);
      tab[cur * 3].push_back(cur * 3 + 1);
      tab[cur * 3 + 1].push_back(cur * 3 + 2);
      tab[cur * 3 + 1].push_back(cur * 3 + 3);
      if (k & 1)
         tab[cur * 3 - 1].push_back(N);
      k = k / 2;
      debug(k);
      cur++;
   }
   cout << N << endl;
   for (int i = 1; i <= N; i++) {
      wypisz(tab[i]);
   }
}