#include <iostream>
#include <istream>

#include<string.h>
using namespace std;

typedef struct bitree
{
    char data;
    struct bitree* left;
    struct bitree* right;
}BiTree;



BiTree * creat (string sq,string sz)
{
    int L = sq.size();
    if(L == 0)return NULL;
    BiTree *root = (BiTree*)malloc(sizeof(BiTree));
    root->data = sq[0];
    int pos = sz.find(sq[0]);
    root->left = creat(sq.substr(1,pos),sz.substr(0,pos));
    root->right = creat(sq.substr(pos+1,L-pos),sz.substr(pos+1,L-pos));
    return root;
}

void PostOrder(BiTree* t)
{
    if(t==NULL)
    {
        return;
    }
    PostOrder(t->left);
    PostOrder(t->right);
    cout<<t->data;
}

int main() {
    string sq,sz;
    while(cin>>sq>>sz)
    {
        BiTree* t = creat(sq,sz);
        PostOrder(t);
    }
}
// 64 位输出请用 printf("%lld")