#include <bits/stdc++.h>

using namespace std;

    char s[3123];
    char t[3123];
    int dp[3123][3123];
    string resp;

int main() {
    scanf(" %s", s+1);
    scanf(" %s", t+1);
    //printf("%s\n", s+1);
    //printf("%s\n", t+1);
    dp[0][0] = 0;
    int max1 = strlen(s+1);
    int max2 = strlen(t+1);

    for(int i = 1; i<= max1; i++){

        for(int j = 1; j<=max2; j++){
            if(s[i] == t[j]){
               dp[i][j] = dp[i-1][j-1] +1;
                //printf("i = %d j = %d\n", i, j);

            }
            else  dp[i][j] = max(dp[i-1][j], dp[i][j-1]);

        }


    }
    int aux = max1;
    int aux2 = max2;

    while(aux > 0 && aux2 > 0){

        if(s[aux] == t[aux2]){
            resp.push_back(s[aux]);
            aux--;
            aux2--;
        }
        else{
            if(dp[aux][aux2-1]>dp[aux-1][aux2] ) aux2--;
            else aux--;


        }
    }

    for(int i = resp.size()-1; i >= 0 ; i-- ) printf("%c", resp[i]);

    return 0;
}