#include <bits/stdc++.h>
#define LIM 1<<17
/// TONI BO$$ was here
/// #MLC

using namespace std;

char BUF[LIM];
int poz;

inline char getChar(){
    poz++;
    if(poz>=LIM){
    	fread(BUF,LIM,1,stdin);
    	poz=0;
    }
    return BUF[poz];
}

inline int getNr(){
    int r=0, semn=1;
    char ch=getChar();
    while(isdigit(ch)==0 && ch!='-') ch=getChar();
    if(ch=='-'){
        semn=-1;
        ch=getChar();
    }
    while(isdigit(ch)!=0){
        r=r*10+semn*(ch-'0');
        ch=getChar();
    }
    return r;
}

struct node
{
    int val;
    long long freq;
    node *leftChild;
    node *rightChild;
    bool operator <(const node &oth) const
    {
        return freq > oth.freq;
    }
};

struct Compare
{
    bool operator ()(node *x1, node *x2){
    return x1->freq > x2->freq;}
};

priority_queue <node *, vector <node *>, Compare> q;

long long code[1000001];
int level[1000001];

void dfs(node *cur, int lev, long long nr)
{
    if(cur->val)
    {
        level[cur->val] = lev;
        code[cur->val] = nr;
        return ;
    }
    dfs(cur->leftChild, lev + 1, nr << 1);
    dfs(cur->rightChild, lev + 1, (nr << 1) + 1);
}

int main()
{
    int n, i, f;
    freopen("huffman.in","r",stdin);
    freopen("huffman.out","w",stdout);
    poz = LIM;
    n = getNr();
    long long sum = 0;
    for(i = 1; i <= n; i++)
    {
        f = getNr();
        node *aux = (node *) malloc(sizeof(node));
        aux->val = i;
        aux->freq = f;
        aux->leftChild = nullptr;
        aux->rightChild = nullptr;
        q.push(aux);
    }
    while(true)
    {
        node *x1 = q.top();
        q.pop();
        if(q.empty())
        {
            q.push(x1);
            break;
        }
        node *x2 = q.top();
        q.pop();
        node *x3 = (node *) malloc(sizeof(node));
        x3->val = 0;
        x3->freq = x1->freq + x2->freq;
        sum += x3->freq;
        x3->leftChild = x1;
        x3->rightChild = x2;
        q.push(x3);
    }
    printf("%lld\n", sum);
    node *start = q.top();
    dfs(start, 0, 0);
    for(i = 1; i <= n; i++)
        printf("%d %lld\n", level[i], code[i]);

    return 0;
}