#include <bits/stdc++.h>
using namespace std;
string s1,s2,t;
void dfs(int l1,int r1,int l2,int r2){
    if(l1>r1||l2>r2) return;
    int m=s2.find(s1[l1]);
    dfs(l1+1,l1+m-l2,l2+1,m-1);
    dfs(l1+m-l2+1,r1,m+1,r2);
    cout<<s1[l1];
}
int main()
{
    cin>>s1>>s2;
    t=s1;
    s1=s2;
    s2=t;
    int r1=s1.length()-1;
    int r2=s2.length()-1;
    dfs(0,r1,0,r2);
    return 0;
}

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