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#include <bits/stdc++.h>
 
#define f first
#define s second
#define pb push_back
#define mp make_pair
 
#define ins insert
#define er erase
 
#define siz size()
#define siz1 size()-1
 
#define ll long long
#define ull unsigned long long
#define all(v) v.begin(), v.end()
 
#define FORN(i, n) for(int i=1; i<=(int)n; i++)
#define FOR(i,p,k) for(int i=(int)p; i<=(int)k; i++)
#define FORD(i, k, p) for(int i=(int)k; i>=(int)p; i--)
#define FOR0(i, n) for(int i=(int)n; i>=0; i--)
#define FOR1(i, n) for(int i=(int)n; i>=1; i--)
#define FORV(i, vec) for(auto i = vec.begin(); i != vec.end(); ++i)

#define TURBO ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define END cerr<<"TIME: "<<1.0 * clock() / CLOCKS_PER_SEC<<endl;
#define VI vector <int>
#define VP vector <pair<int, int>>
#define VIP vector <pair<int, pair<int, int>>>
#define VPP vector <pair<pair<int, int>, pair<int, int>>>
 
#define MII map<int, int>
#define MLL map<ll, ll>
 
#define PII pair<int, int>
#define PLL pair<ll, ll>
 
#define MAX 1e9 + 10
#define MIN -1e9 + 10

using namespace std;

int RESULT[100+5][2];


int main()
{
	TURBO;
	int k;
	
	cin>>k;
	for(int i=1; i<=100; i++)
	{
		RESULT[i][0] = -1;
		RESULT[i][1] = -1;
	}

	int akt_w = 1;
	while(k > 0)
	{
		if(k % 2 && k > 1)
		{
			RESULT[akt_w][0] = akt_w + 1;
			RESULT[akt_w][1] = akt_w + 2;
			
			RESULT[akt_w + 1][0] = akt_w + 3;	
			RESULT[akt_w + 1][1] = 100;		

			RESULT[akt_w + 2][0] = akt_w + 3;
			akt_w += 3;
			
			k -= 1;
			k /= 2;
		}
	
		else if(k==1)
		{
			RESULT[akt_w][0] = 100;
			k -= 1;
		}

		else
		{
			RESULT[akt_w][0] = akt_w + 1;
			RESULT[akt_w][1] = akt_w + 2;
			
			RESULT[akt_w + 1][0] = akt_w + 3;			
			RESULT[akt_w + 2][0] = akt_w + 3;
			akt_w += 3;
			k /= 2;
			
		}
	}
	

	cout<<100<<'\n';
	for(int i=1; i<=100; i++)
		cout<<RESULT[i][0]<<" "<<RESULT[i][1]<<'\n';

	
	return 0;
}