#include <iostream>
#include <string> 
using namespace std;
string s1, s2;
int len;
int k = 0;
void dfs(int l, int r)
{
	if (l > r)
	{
		return ;
	}
	int root = s2.find(s1[k++], l);
	dfs(l, root - 1);
    dfs(root + 1, r);
    cout << s2[root];
    return ;
}
int main()
{
	cin >> s2 >> s1;
	len = s2.size();
	dfs(0, len - 1);
	return 0;
}