#include<bits/stdc++.h>
using namespace std;
const int N =100000;
int lson[N],rson[N];char in[N],po[N],ans[N];
int cnt = 1;
void dfs(int u,int m1,int m2,int s1,int s2)
{
	ans[m2] = po[s1];
	int t=0;
	for(int i=m1;i<=m2;++i)
	{
		if(po[i]==ans[m2]) t = i;
	}
	if(t!=m1)
	{
		lson[u] = ++cnt;
		dfs(lson[u],m1,t-1,s1,s1+(t-m1-1));
	}
	if(t!=m2)
	{
		rson[u] = ++cnt;
		dfs(rson[u],t+1,m2,s1+t-m1,s2-1);
	}
}
void print(int u) 
{
	cout<<ans[u];
	if(lson[u]) print(lson[u]);
	if(rson[u]) print(rson[u]);
}
int main()
{
	cin>>po>>in;
	int sl = strlen(in);
	dfs(1,0,sl-1,0,sl-1);
	print(1);
	return 0;
}