#include <cstdio>
#include <vector>

#define In "huffman.in"
#define Out "huffman.out"
#define LL long long
#define PLLN pair < LL , node* >
#define PLS pair < LL , short >
#define Nmax 1000002

using namespace std;

struct node
{
    node *l, *r;
//    int ind;
    node()
    {
  //      ind = 0;
        l = r = NULL;
    }
};
PLS sol[Nmax];
node *Root = new node;
PLLN A[Nmax];
PLLN B[Nmax];
int N, LA, LB, indA, indB,ind = 1;
LL Sum;
inline void Read()
{
    freopen(In,"r",stdin);
    freopen(Out,"w",stdout);
    scanf("%d",&N);
    int x;
    node *X;
    for(int i = 1;i <= N ; ++i)
    {
        scanf("%d",&x);
        X = new node;
    //    X->ind = i;
        A[++LA] = make_pair(x,X);
    }
}

inline PLLN Min()
{
    PLLN X;
    X.first = 0;
    if(indA>LA && indB>LB)
        return X;
    if(indA>LA)
        return B[indB++];
    if(indB>LB)
        return A[indA++];
    if(A[indA] < B[indB])
        return A[indA++];
    return B[indB++];
}

inline void BuildTree()
{
    PLLN X, Y;
    node *A,*Last;
    indA = indB  = 1;
    while(true)
    {
        X = Min();
        Y = Min();
        if(X.first<=0 || Y.first<=0)
        {
            Root = Last;
            return;
        }
        A = new node;
        A->l = X.second;
        A->r = Y.second;
        Sum += X.first+Y.first;
        Last = A;
        B[++LB] = make_pair(X.first+Y.first,A);
    }
}

inline void BuildSol(node *_node,const LL X, const short length)
{
    if(!_node->l && !_node->r)
    {
        sol[ind].first = X;
        sol[ind].second = length;
        ind++;
        return;
    }
    if(_node->l)
        BuildSol(_node->l,(X<<1),length+1);
    if(_node->r)
        BuildSol(_node->r,(X<<1)+1,length+1);
}

inline void Write()
{
    printf("%lld\n",Sum);
    for(int i = 1;i <= N; ++i)
         printf("%hd %lld\n",sol[i].second,sol[i].first);
    printf("\n");
}

int main()
{
    Read();
    BuildTree();
    BuildSol(Root,0,0);
    Write();
    return 0;
}