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#include<bits/stdc++.h>
using namespace std;

int main(void){
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);

	int k;
	cin >> k;

	vector<pair<int,int> > t;

	for(int i=0;i<30;i++)
		t.push_back({i+1,-2});
	t.back().first = -2;

	int free=0;
	int msb=30;
	while(!(k&(1<<msb)))
		msb--;
	msb--;

	while(msb >= 0){
		int last = t.size()-1;

		t[last] = {last+1,last+2};
		t.push_back({last+2,-2});
		t.push_back({-2,-2});

		if(k&(1<<msb))
			t[free++].second = last+2;

		msb--;
	}

	cout << t.size() << "\n";
	for(auto& i : t)
		cout << i.first+1 << " " << i.second+1 << "\n";

	return 0;
}