#include<bits/stdc++.h>
#define maxn 3200
using namespace std;
typedef long long LL;
char s[maxn], t[maxn];
int f[maxn][maxn];
int main(){
	ios::sync_with_stdio(false);
	cin >> s + 1 >> t + 1;
	int n = strlen(s + 1), m = strlen(t + 1);
	for(int i = 1; i <= n; i += 1)
		for(int j = 1; j <= m; j += 1)
			if(s[i] == t[j]) f[i][j] = f[i - 1][j - 1] + 1;
			else f[i][j] = max(f[i - 1][j], f[i][j - 1]);
	string ans;
	while(f[n][m]){
		if(s[n] == t[m]){
			ans.push_back(s[n]);
			n -= 1;
			m -= 1;
		}
		else if(f[n - 1][m] == f[n][m]) n -= 1;
		else m -= 1;
	}
	reverse(ans.begin(), ans.end());
	cout << ans;
} 