import java.util.*;
import java.lang.*;
import java.io.*;

public class Main
{
    public static void main (String[] args) throws java.lang.Exception
    {
      Scanner sc=new Scanner(System.in);
      String s=sc.next();
      String p=sc.next();
      if(s.length()<p.length()){
        System.out.print("-1");
        return;
      }
      int n = s.length();
      int m = p.length();
      int pchar[] = new int[26];
      for(int i =0; i < m; i++){
        pchar[p.charAt(i)-'a']++;
      }
      int window[] = new int[26];
      int i = 0;
      int j = 0;
      int ans = 1000000;
      int index = 0;
      while( j < n) {
        window[s.charAt(j)-'a']++;
        int flag = 1;
        for(int k = 0; k < 26;k++) {
             if(pchar[k] != 0 && window[k] == 0 ) {
               flag = 0;
               break;
             }
        }
        if(flag  == 1) {

          while(true) {
            //System.out.println(ans + " " + i + " " + j);
              if(ans > j - i + 1) {
              ans = j - i + 1;
               // System.out.println(ans);
              index = i;
             }
             if(pchar[s.charAt(i)-'a'] !=0 && window[s.charAt(i)-'a'] ==1) {
                  window[s.charAt(i)-'a']--;
                  i++;
                  break;
             }
            else {
                window[s.charAt(i)-'a']--;
            }
            i++;
            //System.out.println(i);
        }


        }
        j++;
      }
      if(ans == 1000000) {
        System.out.print("-1");
      }
      else {
        System.out.print(s.substring(index,index + ans));
      }

    }
}