#include "bits/stdc++.h"
using namespace std;
int dp[3001][3001];
int main()
{
	string s, t, ans = "\n";
	cin >> s >> t;	
	int m = s.length(), n = t.length();
	for(int i = 1; i <= m; ++i)
	{
		for(int j = 1; j <= n; ++j)
		{
			if(s[i - 1] == t[j - 1])
			{
				dp[i][j] = max(dp[i][j], dp[i - 1][j - 1] + 1);
			}
			dp[i][j] = max(dp[i][j], max(dp[i - 1][j], dp[i][j - 1]));
		}
	}
	for(int x = m, y = n; x && y; )
	{
		if(dp[x][y] == dp[x - 1][y])
		{
			--x;
		}
		else if(dp[x][y] == dp[x][y - 1])
		{
			--y;
		}
		else
		{
			ans = s[x - 1] + ans;
			--x;
			--y;
		}
	}
	cout << ans;
}
