#include<bits/stdc++.h>
#include<atcoder/all>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef vector<int> vi;
typedef vector<long long> vl;
typedef vector<vector<int>> vvi;
typedef vector<vector<long long>> vvl;
typedef long double ld;
typedef pair<int, int> P;

ostream& operator<<(ostream& os, const modint& a) {os << a.val(); return os;}
template <int m> ostream& operator<<(ostream& os, const static_modint<m>& a) {os << a.val(); return os;}
template<typename T> istream& operator>>(istream& is, vector<T>& v){int n = v.size(); assert(n > 0); rep(i, n) is >> v[i]; return is;}
template<typename U, typename T> ostream& operator<<(ostream& os, const pair<U, T>& p){os << p.first << ' ' << p.second << "\n"; return os;}
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : " "); return os;}
template <typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : ""); return os;}

int main(){
	int n;
	cin >> n;
	vl a(n);
	cin >> a;
	int m = 62;
	vi g(m, -1);
	int minus = 0;
	auto func = [&](long long x){
		vi cnt(m);
		if(x < 0) return 16;
		rep(i, m){
			if((x >> i) & 1){
				cnt[g[i]]++;
			}
		}
		rep(i, m) if(cnt[i] == 0) return i;
		assert(true);
		return 0;
	};
	rep(i, m) g[i] = func(i);
	int prod = 0;
	rep(i, n){
		prod ^= func(a[i]);
	}
	if(prod != 0) cout << 1 << "\n";
	else cout << 2 << "\n";
	rep(i, m){
		cout << i << ' ' << func(i) << "\n";
	}
	return 0;
}