#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
#include <deque>
using namespace std;
typedef unsigned long long ull;
 
struct node {
    node() { data=-1; freq=1<<30; }
    int child[2];
    ull freq;
    int data;
};
vector<node> a;
vector<ull> code;
 
void hufftree() {
    int n=a.size();
    int fr1=0, fr2=n;
    for (int j=1; j<n; ++j) {
        a.push_back(node());
        for (int i=0; i<2; ++i) {
            if (fr1==n ||  a[fr2].freq < a[fr1].freq) {
                a.back().child[i]=fr2++;
            }
            else {
                a.back().child[i]=fr1++;
            }
        }
        a.back().freq = a[a.back().child[0]].freq + a[a.back().child[1]].freq;
    }
}
 
void store(node & tmp, ull num, ull & len) {
    len+=tmp.freq;
    if (tmp.data!=-1) {
        code[tmp.data]=num;
        return;
    }
    store(a[tmp.child[0]], num<<1, len);
    store(a[tmp.child[1]], (num<<1)+1, len);
}
 
int main() {
    freopen("huffman.in","r",stdin);
    freopen("huffman.out","w",stdout);
    //ifstream fin("huffman.in");
    //ofstream fout("huffman.out");
    int n; scanf("%d",&n);
    a.reserve(2*n-1);
    a.resize(n);
    for (int i=0; i<n; ++i) {
        a[i].data=i;
        scanf("%lld",&a[i].freq);
    }
    hufftree();
    code.resize(n);
    ull len=0;
    store(a.back(), 1ull, len);
    printf("%lld\n",len-a.back().freq);
    //fout << len-a.back().freq << '\n';
    for (int i=0; i<n; ++i) {
        unsigned int tmp=63-__builtin_clzll(code[i]);
        printf("%u %lld \n", tmp, (code[i]^(1ull<<tmp)));
    }
    return 0;
}