#include <bits/stdc++.h>
using namespace std;
ifstream in("huffman.in");
ofstream out("huffman.out");
using ll = long long;
const int lim = 2e6+4;
const ll inf = 4e18;
queue<int> frunze;
queue<int> artificiale;
ll freq[lim];
int lefty[lim];
int righty[lim];
int deep[lim];
int ans[lim];
int n, cnt;
void df(int nod) {
	if(nod <= n) {
		return ;
	}
	deep[lefty[nod]] = deep[righty[nod]] = deep[nod] + 1;
	ans[lefty[nod]] = ans[righty[nod]] = ans[nod];
	ans[righty[nod]] |= (1LL<<deep[nod]);
	
	df(lefty[nod]);
	df(righty[nod]);
}
int main() {
	in>>n;
	for(int i=1;i<=n;++i) {
		in>>freq[i];
		frunze.push(i);
	}
	cnt = n;
	for(int iter=n;iter>=2;--iter) {
		int n[2];
		for(int i=0;i<2;++i) {
			ll lmin = inf, rmin = inf;
			if(!frunze.empty()) {
				lmin = freq[frunze.front()];
			}
			if(!artificiale.empty()) {
				rmin = freq[artificiale.front()];
			}
			if(lmin<=rmin) {
				n[i] = frunze.front();
				frunze.pop();
			} else {
				n[i] = artificiale.front();
				artificiale.pop();
			}
		}
		++cnt;
		freq[cnt] = freq[n[0]] + freq[n[1]];
		artificiale.push(cnt);
		lefty[cnt] = n[0];
		righty[cnt] = n[1];
	}
	df(cnt);
	ll sum = 0;
	for(int i=1;i<=n;++i) {
		sum += freq[i]*deep[i];
	}
	out<<sum<<'\n';
	for(int i=1;i<=n;++i) {
		out<<deep[i]<<' '<<((1LL<<deep[i])-1)^ans[i]<<'\n';
	}
	return 0;
}