ac

import java.util.Scanner;


public class Main {

    public static Scanner sc = new Scanner(System.in);

    public static void main(String[] args) {
        String s1 = sc.nextLine();
        String s2 = sc.nextLine();

//        String s1 = "1AB2345CD";
//        String s2 = "12345EF";

        int n1 = s1.length();
        int n2 = s2.length();
        char[] arr1 = s1.toCharArray();
        char[] arr2 = s2.toCharArray();

        int maxLen = 0;
        int maxI = 0;
        // 斜着的一一计算
        int si = 0;
        int sj = n1 -1;
        while (true){
            if(si == n2-1 && sj == 0){
                break;
            }
            int len = 0;
            int i = si;
            int j = sj;
            if(arr2[i] == arr1[j]){
                len = 1;
            }
            if(len > maxLen){
                maxLen = len;
                maxI = i;
            }
            while (i < n2 && j < n1){
                i++;
                j++;
                if(i >= n2 || j >= n1){
                    break;
                }
                if(arr2[i] == arr1[j]){
                    len = len + 1;
                }else {
                    len = 0;
                }
//                System.out.println(i + " " + j + " " + len);
                if(len > maxLen){
                    maxLen = len;
                    maxI = i;
                }
            }
            if(sj > 0){
                sj --;
            }else{
                si ++;
            }
        }

        if(maxLen == 0){
            System.out.println(-1);
            return;
        }
        String ans = "";
        while (maxLen-- > 0){
            ans = arr2[maxI] + ans;
            maxI--;
        }
        System.out.println(ans);
    }


}
/*
1AB2345CD
12345EF

2345
*/

import java.util.Scanner;


public class Main {

    public static Scanner sc = new Scanner(System.in);

    public static void main(String[] args) {
        String s1 = sc.nextLine();
        String s2 = sc.nextLine();

//        String s1 = "1A2C3D4B56";
//        String s2 = "B1D23CA45B6A";

        int n1 = s1.length();
        int n2 = s2.length();
        char[] arr1 = s1.toCharArray();
        char[] arr2 = s2.toCharArray();

        int maxLen = 0;
        int maxI = 0;
        int[][] dp = new int[n2][n1];
        for(int i=0;i<n2;i++){
            if(arr1[0] == arr2[i]){
                dp[i][0] = 1;
                maxLen = 1;
                maxI = i;
            }
        }
        for(int i=0;i<n1;i++){
            if(arr2[0] == arr1[i]){
                dp[0][i] = 1;
                maxLen = 1;
                maxI = 0;
            }
        }

        for(int i=1;i<n2;i++){
            for(int j=1;j<n1;j++){
                if(arr2[i] == arr1[j]){
                    dp[i][j] = dp[i-1][j-1] + 1;
                }
                if(dp[i][j] > maxLen){
                    maxLen = dp[i][j];
                    maxI = i;
                }
            }
        }
//        for(int i=0;i<n2;i++){
//            for(int j=0;j<n1;j++){
//                System.out.print(dp[i][j] + " ");
//            }
//            System.out.println();
//        }
        if(maxLen == 0){
            System.out.println(-1);
            return;
        }
        String ans = "";
        while (maxLen-- > 0){
            ans = arr2[maxI] + ans;
            maxI--;
        }
        System.out.println(ans);
    }


}
/*
1AB2345CD
12345EF

2345
*/