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