#include <iostream>
#include <string>
using namespace std;
int dp[3010][3010] = {};
int main(){
	string s,t,u;
	cin >> s >> t;
	int i,j;
	for(i=1;i<=s.size();i++){
		for(j=1;j<=t.size();j++){
			dp[i][j] = max(dp[i-1][j],dp[i][j-1]);
			if(s[i-1]==t[j-1]) dp[i][j] = dp[i-1][j-1] + 1;
		}
	}
	i = s.size(), j = t.size();
	while(i>0 && j>0){
		if(dp[i-1][j]==dp[i][j]) i--;
		else if(dp[i][j-1]==dp[i][j]) j--;
		else{
			i--; j--;
			u.push_back(s[i]);
		}
	}
	for(i=0;i<u.size();i++){
		cout << u[u.size()-1-i] ;
	}
	cout << endl;
}