#include<bits/stdc++.h>
using namespace std;
#define MAX 1000
char str1[MAX],str2[MAX];
int lenA,lenB;
int dp[MAX][MAX];
bool visited[MAX][MAX];
int LCS(int i,int j)
{
	if(str1[i]=='\0' || str2[j]=='\0') return 0;
	if(visited[i][j])return dp[i][j];

	int ans=0;
	if(str1[i]==str2[j]) ans=1+LCS(i+1,j+1);
	else
	{
		int val1=LCS(i+1,j);
		int val2=LCS(i,j+1);
		ans=max(val1,val2);
	}
	visited[i][j]=1;
	dp[i][j]=ans;
	return dp[i][j];
}
string ans;
void printLCS(int i,int j)
{
    if(str1[i]=='\0' or str2[j]=='\0'){
        cout<<ans<<endl;
        return;
    }
    if(str1[i]==str2[j]){
        ans+=str1[i];
        printLCS(i+1,j+1);
    }
    else
    {
        if(dp[i+1][j]>dp[i][j+1]) printLCS(i+1,j);
        else printLCS(i,j+1);
    }
}
int main() {
	scanf("%s%s",str1,str2);
	lenA=strlen(str1);
	lenB=strlen(str2);
	LCS(0,0);
	printLCS(0,0);
	return 0;

}