#include <iostream>
using namespace std;
#include <cstdio>
#include <cstring>

string s1,s2;

void work(int l1,int r1,int l2,int r2)
{
	int m=s2.find(s1[l1]);
	if (m==-1) return;
	if (m>l2) work(l1+1,l1+m-l2,l2,m-1);
	if (m<r2) work(l1+m-l2+1,r1,m+1,r2);
	cout<<s1[l1];
}

int main()
{
	cin>>s1; s1=' '+s1;
    cin>>s2; s2=' '+s2;
	work(1,s1.size(),1,s2.size());
	cout<<endl;
}