#include <bits/stdc++.h>

using namespace std;

string pre, in;

int length;

char ans[];

void process(int l, int r){

    if(l > r) return;

    bool flag = false;

    char ch;

    int mid;

    for(int i = ; i < pre.length(); ++i){

        for(int j = l; j <= r; ++j){

            if(pre[i] == in[j]){

                flag = true;

                ch = pre[i];

                mid = j;

                break;

            }

        }

        if(flag) break;

    }

    ans[--length] = ch;

　　//注意先右后左(后序遍历从左到右再到根)

    process(mid + , r);

    process(l, mid - );

}

int main(){

    while(cin >> pre >> in){

        length = pre.length();

        process(, length - );

        for(int i = ; i < pre.length(); ++i) cout << ans[i];

        cout << endl;

    }

    return ;

}