#include<bits/stdc++.h>
using namespace std;
const int MAX = 3001;
int dp[MAX][MAX];
int main() {
	string s,t,lcs;
	cin>>s>>t;
	int i,j,ns = s.size(), nt = t.size();
	for(i=1;i<=ns;++i) {
		for(j=1;j<=nt;++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 ps = ns, pt = nt;
	while(ps > 0 and pt > 0) {
	    if(s[ps-1] == t[pt-1]) {
	        lcs.push_back(s[ps-1]);
	        ps--; pt--;
	    } else {
	        if(dp[ps][pt] == dp[ps][pt-1]) pt--;
	        else ps--;
	    }
	    
	}
	reverse(lcs.begin(), lcs.end());
	cout<<lcs<<endl;
	return 0;
}