#include<bits/stdc++.h>
using namespace std;
string dp[3010][3010];
string a,b;
int lena,lenb;
int main(){
	cin>>a>>b;
	lena=a.size(),lenb=b.size();
	a=" "+a,b=" "+b;
	for(int i=1;i<=lena;i++){
		for(int j=1;j<=lenb;j++){
			if(a[i]==b[j]){
				dp[i][j]=dp[i-1][j-1]+a[i];
			}else{
				dp[i][j]=dp[i-1][j].size()<dp[i][j-1].size()?dp[i][j-1]:dp[i-1][j];
			}
		}
	}
	cout<<dp[lena][lenb]<<'\n';
	return 0;
}