#include <iostream>
#include <fstream>
#include <algorithm>
#include <math.h>
#define MAX_HEAP_SIZE 1000001

using namespace std;
ifstream in;
ofstream out;
unsigned long long int heap [MAX_HEAP_SIZE], n, Q[MAX_HEAP_SIZE], pos[MAX_HEAP_SIZE], LU[MAX_HEAP_SIZE], ST[MAX_HEAP_SIZE], DR[MAX_HEAP_SIZE], nr, c=1, T, viz[MAX_HEAP_SIZE], NUMAR_AIUREA, lg[MAX_HEAP_SIZE], b[MAX_HEAP_SIZE];
char cod [64];int contor, contor2;

int defeu (int k)
{
    NUMAR_AIUREA=0;
    viz[k]=1;
    if(ST[k] && DR[k])
    {
        if(!viz[ST[k]])
        {
            cod[contor]=0;
            ++contor;
            defeu(ST[k]);

        }
        if(!viz[DR[k]])
        {
            cod[contor]=1;
            ++contor;
            defeu(DR[k]);

        }
    }
    else
    {
    lg[k]=contor;
    for(int j=0;j<contor;++j)
        NUMAR_AIUREA+=pow(2, contor-1-j) * cod[j];
    b[k]=NUMAR_AIUREA;
    }
    --contor;


}
void sift(unsigned long long int * h,unsigned long long int i)   ///down
{
    int k, j=0;
    k=i;
    while(j!=k)
    {
        j=k;
        if((2*j<=nr ) && (h[2*j] < h[k]))
           k=2*j;
        if((2*j<nr) && (h[2*j+1]< h[k]))
            k=2*j+1;
        swap(h[j], h[k]);
        swap(pos[j], pos[k]);
    }
}
void percolate(unsigned long long int * h, unsigned long long int i)  ///up
{
    int k, j=0;
    k=i;
    while(j!=k)
    {
        j=k;
        if((j>1) && (h[j/2]>h[k]))
            k=j/2;
        swap(h[j], h[k]);
        swap(pos[j], pos[k]);
    }
}
unsigned long long int  find_min(unsigned long long int *h)
{
    return h[1];
}
void delete_max(unsigned long long int * h)
{
    h[1]=h[nr];
    pos[1]=pos[nr];
    //--nr
    sift(h, 1);
}
void insert_heap(unsigned long long int * h, unsigned long long int val)
{
    h[nr]=val;
    //pos[nr]=nr;
    pos[nr]=c;
    ++c;
    percolate(h, nr);
}
///PANA AICI AU FOST PORCARIILE ALEA DE LA HEAP
int main()
{
    in.open ("huffman.in");
    out.open ("huffman.out");
    in>>n;
    for(int i = 1;i<=n;++i)
    {
        in>>Q[i];       ///lungimile sirurilor
        ++nr;
        insert_heap(heap, Q[i]);
        LU[i]=Q[i];
        ST[i]=0;
        DR[i]=0;
    }
    ///amu algoritmu propriu-zis
    int s, j, r, k;
        /*cout<<"Heapul cu "<<nr<<" elem: ";
        for(int j=1;j<=nr;++j)
            cout<<heap[j]<<" ";
        cout<<endl;
        for(int j=1;j<=n;++j)
            cout<<pos[j]<<" ";
        cout<<"\n\n";*/
    for(int i=n+1;i<2*n;++i)
    {
        ///luam doua cele mai scurte siruri
        s=find_min(heap);
        j=pos[1];
        delete_max(heap);
        --nr;
        r=find_min(heap);
        k=pos[1];
        delete_max(heap);
        --nr;
        ST[i]=j;
        DR[i]=k;
        LU[i]=s+r;
        ++nr;
        insert_heap(heap, LU[i]);
    }
    for(int i=n+1;i<2*n;++i)
        T+=LU[i];
   // for(int i =1;i<2*n;++i)
     //   cout<<ST[i]<<" "<<LU[i]<<" "<<DR[i]<<"\n";
    out<<T<<"\n";
    defeu(2*n-1);
    for(int i=1;i<=n;++i)
        out<<lg[i]<<" "<<b[i]<<"\n";
    in.close();
    out.close();
    return 0;
}