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#include <bits/stdc++.h>
 
#define st first
#define nd second
#define pb push_back
#define BOOST ios_base::sync_with_stdio(0); cout.tie(0); cin.tie(0);
#define PI 3.14159265359
 
using namespace std;
 
typedef long long ll;
constexpr ll MOD = 1000000007, hot = 29;
constexpr ll FOX = 1234567891, cute = 1009;
constexpr ll MEGAN = 1000000009, liv = 107;
constexpr int MXN = 1000000+7 + 10, CZAPA = (1<<20), INF = 1000000000;

int edges[107][2];

int main(){	
	BOOST;	

	int k;
	cin>> k;
	if(k == 1){
		cout<< "2\n2 -1\n-1 -1\n";
		return 0;
	}
	int idx = 1;
	while((1<<idx) <= k) idx++;
	idx--;
	int n = 2 * (idx+1);
	for(int i=1; i<=n-2; i++){
		if(i % 2 == 0){
			edges[i][0] = i+1;
		}
		else{
			edges[i][0] = i+1;
			edges[i][1] = i+2;
		}
	}
	edges[n-1][0] = n;
	for(int i=0; i<idx; i++){
		if(((1<<i)&(k)) > 0){
			edges[2*(i+1)][1] = n;
		}
	}
	cout<< n << '\n';
	for(int i=1; i<=n; i++){
		if(edges[i][0] == 0) edges[i][0] = -1;
		if(edges[i][1] == 0) edges[i][1] = -1;
		cout<< edges[i][0] << ' ' << edges[i][1] << '\n';
	}


	return 0;
}