import java.util.*;
public class Main {
public static void main(String args[]) {
// Your Code Here
Scanner scn=new Scanner(System.in);
String s1=scn.next();
String s2=scn.next();
PRINTLCS(s1,s2);
}
public static void PRINTLCS(String s1, String s2) {
int strg[][] = new int[s1.length() + 1][s2.length() + 1];
for (int row = s1.length(); row >= 0; row--) {
for (int col = s2.length(); col >= 0; col--) {
if (row == s1.length()) {
strg[row][col] = 0;
continue;
}
if (col == s2.length()) {
strg[row][col] = 0;
continue;
}
if (s1.charAt(row) == s2.charAt(col)) {
strg[row][col] = 1 + strg[row + 1][col + 1];
} else {
strg[row][col] = Math.max(strg[row + 1][col], strg[row][col + 1]);
}
}
}
String ans = "";
int i = 0;
int j = 0;
while (i < s1.length() && j < s2.length()) {
if (strg[i][j] == strg[i + 1][j] && strg[i][j] == strg[i][j + 1]) {
j++;
} else if (strg[i + 1][j] == strg[i][j + 1]) {
ans += s1.charAt(i);
i++;
j++;
} else if (strg[i + 1][j] != strg[i][j + 1]) {
if (strg[i + 1][j] > strg[i][j + 1]) {
i++;
} else {
j++;
}
}
}
System.out.println(ans);
}
}