#include<bits/stdc++.h>
#define mx 3005
using namespace std;

string s, t, ans;
int dp[mx][mx], u, w;

int main(){
	cin >> s >> t;
	u = s.length();
	w = t.length();
	s = "." + s;
	t = "," + t;
	for(int i = 1; i <= u; i++){
		for(int j = 1; j <= w; j++){
			dp[i][j] = max(max(dp[i-1][j], dp[i][j-1]), dp[i-1][j-1] + (s[i] == t[j]));
		}
	}
	while(dp[u][w]){
		if(dp[u][w] == dp[u][w-1]) w--;
		else if(dp[u][w] == dp[u-1][w]) u--;
		else{
			ans = s[u] + ans;
			w--;
			u--;
		}
	}
	cout << ans << endl;
}
