#include <bits/stdc++.h>
using namespace std;
string s1,s2;
void build(int l1,int r1,int l2,int r2)
{
    int root=l1,p=l2;
    if(l1>r1) return;
    while(s2[p]!=s1[root] && p<=r2) p++;
    int cnt=p-l2;
    build(l1+1,l1+cnt,l2,p-1);
    build(l1+cnt+1,r1,p+1,r2);
    printf("%c",s1[root]);
}
int main()
{
    while(cin>>s1>>s2)
    {
        build(0,s1.length()-1,0,s2.length()-1);
        puts("");
    }
    return 0;
}