#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 4000000000000000001

vector<vector<int>> is(30);
vector<int> a;
int X = 0;

void Go(){
	int m = 29;
	for(int i=29;i>=0;i--){
		if((X>>i)&1){
			m = i;
			break;
		}
	}
	
	while(true){
		int ii = is[m].back();
		is[m].pop_back();
		if((a[ii]>>m)&1){
			cout<<ii+1<<' '<<a[ii] - (a[ii]^X)<<endl;
			a[ii] ^= X;
			X = 0;
			rep(j,30){
				if((a[ii]>>j)&1)is[j].push_back(ii);
			}
			break;
		}
	}
	
	int r;
	cin>>r;
	if(r==-1)exit(0);
}

void Other(){
	int i,k;
	cin>>i>>k;
	i--;
	X ^= a[i];
	a[i] -= k;
	X ^= a[i];
	rep(j,30){
		if((a[i]>>j)&1)is[j].push_back(i);
	}
	int r;
	cin>>r;
	if(r==-1)exit(0);
	
}

int main(){
	
	int n;
	cin>>n;
	
	a.resize(n);
	rep(i,n){
		scanf("%d",&a[i]);
		rep(j,30){
			if((a[i]>>j)&1)is[j].push_back(i);
		}
		X ^= a[i];
	}
	
	if(X!=0){
		cout<<1<<endl;
		Go();
	}
	else{
		cout<<0<<endl;
	}
	
	while(true){
		Other();
		Go();
	}
	
	
	return 0;
}