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#pragma GCC optimize ("Ofast")
#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define FOR(i, a, b) for (int i=(a); i<(b); i++)
#define FORD(i, a, b) for (int i=(a); i>(b); i--)
#define PPC(x) __builtin_popcount(x)
#define MSB(x) (63 - __builtin_clzll(x))
#define SZ(x) ((int)(x).size())
#define HASK(S, x) (S.find(x) != S.end())
#define pb push_back
#define ALL(x) (x).begin(), (x).end()
#define ithBit(m, i) ((m) >> (i) & 1)
#define ft first
#define sd second
#define kw(a) ((a) * (a))
#ifdef DEBUG
#include "debug.h"
#else
#define dbg(...) 0
#endif
using namespace std; 

const int maxN = 101;

vector <int> G[maxN];
int hed[maxN];

long long dp[maxN];

void dfs(int v)
{
	assert(SZ(G[v]) <= 2);
	for (int u : G[v]) if (u != -1)
	{
		if (dp[u] == 0)
			dfs(u);
		dp[v] += dp[u];
	}
}

void solve()
{
	int v = 1;
	hed[0] = ++v;
	FOR(i, 1, 31)
	{
		G[++v].pb(hed[i-1]);
		G[++v].pb(hed[i-1]);
		G[v].pb(v-1);
		hed[i] = v;
	}
	
	int k;
	scanf ("%d", &k);
	
	G[1].pb(++v);
	
	while (k != 0)
	{
		int b = MSB(k);
		k ^= 1 << b;
		G[v].pb(v+1);
		G[++v].pb(hed[b]);
		
	}
	
	G[hed[0]].pb(++v);
	int n = v;
	
	printf("%d\n", n);
	FOR(i, 1, n+1)
	{
		while (SZ(G[i]) < 2)
			G[i].pb(-1);
		printf("%d %d\n", G[i][0], G[i][1]);
	}
	
	dp[n] = 1ll;
	dfs(1);
	dbg(dp[1]);
}
 
int main()
{
	int t = 1;
	//scanf ("%d", &t);
	FOR(tid, 1, t+1)
	{
		//printf("Case #%d: ", tid);
		solve();
	}
	return 0;
}