int input(Node*,int);   //輸入節(jié)點信息
int buildedTree(Node*,int); //建哈夫曼樹
int getMin(Node*,int);  //尋找未使用的，具有最小頻率值的節(jié)點
int outCoding(Node*,int);   //輸出哈夫曼編碼

int main ()
{
    int n;
    cin>>n;
    Node *nodes=new Node[2*n-1];
    input(nodes,n);
    buildedTree(nodes,n);
    outCoding(nodes,n);
    delete(nodes);
    return 0;
}

int input(Node* nodes,int n){
    for(int i=0;i<n;i++){
        cin>>(nodes+i)->c;
        cin>>(nodes+i)->value;
    }
    return 0;
}

int buildedTree(Node* nodes,int n){
    int last=2*n-1;
    int t1,t2;
    for(int i=n;i<last;i++){
        t1=getMin(nodes,i);
        t2=getMin(nodes,i);
        (nodes+t1)->par=i; (nodes+t1)->tag='0';
        (nodes+t2)->par=i; (nodes+t2)->tag='1';
        (nodes+i)->value=(nodes+t1)->value+(nodes+t2)->value;
    }
    return 0;
}

int getMin(Node* nodes,int n){
    int minValue=10000000;
    int pos=0;
    for(int i=0;i<n;i++)
    {
        if((nodes+i)->isUsed == false && (nodes+i)->value<minValue){
            minValue=(nodes+i)->value;
            pos=i;
        }
    }
    (nodes+pos)->isUsed=true;
    return pos;
}

int outCoding(Node* nodes,int n){
    char a[100];
    int pos,k,j;
    char tmp;
    for(int i=0;i<n;i++){
        k=0;
        pos=i;
        memset(a,'\0',sizeof(a));
        while((nodes+pos)->par!=-1){
            a[k++]=(nodes+pos)->tag;
            pos=(nodes+pos)->par;
        }
        strrev(a);    //翻轉(zhuǎn)字符串
        cout<<(nodes+i)->c<<" "<<(nodes+i)->value<<":"<<a<<endl;
    }
    return 0;
}