#include<bits/stdc++.h>
using namespace std;
int a[3005][3005];
signed main()
{
	string s,t;
	cin>>s>>t;
	int l=s.length();
	int n=t.length();
	for(int i=0; i<=l; i++)
	{
		for(int j=0; j<=n; j++)
		{
			if (min(i,j)==0)
				a[i][j]=0;
			else if (s[i-1]==t[j-1])
				a[i][j]=a[i-1][j-1]+1;
			else
				a[i][j]=max(a[i-1][j],a[i][j-1]);
		}
	}
	string ans="";
	int i=l,j=n;
	while(i>0 && j>0)
	{
			if (s[i-1]==t[j-1])
			{
				ans+=s[i-1];
				i-=1;
				j-=1;
			}
			else if (a[i-1][j]>a[i][j-1])
				i-=1;
			else
				j-=1;
	}
	reverse(ans.begin(),ans.end());
	cout<<ans;
}