#include<bits/stdc++.h>
using namespace std;
void dfs(string xx,string zx)
{
	if(!xx.size()) return;
	int pos=zx.find(xx[0]);
	dfs(xx.substr(1,pos),zx.substr(0,pos));
	dfs(xx.substr(pos+1),zx.substr(pos+1));
	cout<<xx[0];
}

int main()
{
	string xx,zx;
	cin>>xx>>zx;
		dfs(xx,zx);
}

求大佬帮忙啊