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

#define REP(i,n) for(int (i)=0; i<(int)(n); i++)

int dp[3010][3010];

int main(void) {
	string s,t,ans = "";
	cin >> s >> t;
	int N=s.size(), M=t.size();
	for(int i=1; i<=N; i++)
		for(int j=1; j<=M; j++) {
			if(s[i-1] == t[j-1]) dp[i][j] = dp[i-1][j-1]+1;
			else dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
		}
	int i = N,j = M;
	while(i > 0 && j > 0) {
		if(dp[i][j] == dp[i-1][j]) i--;
		else if(dp[i][j] == dp[i][j-1]) j--;
		else {
			ans = s[i-1] + ans;
			i--;
			j--;
		}
	}
  	cout << ans << endl;
  	return 0;
}