#include<bits/stdc++.h>
using namespace std;
string a,b;
void xx(int l1,int r1,int l2,int r2)
{
    int mid;
    for(int i=l1;i<=r1;i++)
    {
        if(a[i]==b[r2])
            mid=i;
    }
    cout<<b[r2];
    if(mid!=l1)
        xx(l1,mid-1,l2,l2+mid-l1);
    if(mid!=r1)
        xx(mid+1,r1,l2+mid-l1+1,r2-1);
}
int main()
{
    cin>>a>>b;
    xx(0,(int)a.length(),0,(int)b.length());
    return 0;
}

求救