import java.util.*;

public class Main {

    static boolean isGood(int[] frePtr, int[] freRunning) {
        for(int i = 0; i < 26; i++) {
            if(freRunning[i] < frePtr[i])
                return false;
        }
        return true;
    }

    public static void main (String[] args) throws java.lang.Exception {
        Scanner scanner = new Scanner(System.in);
        String str = scanner.next();
        String ptr = scanner.next();
        int[] frePtr = new int[26];
        int[] freRunning = new int[26]; // sliding window frequency
        for(int i = 0; i < ptr.length(); i++) {
            frePtr[ptr.charAt(i) - 'a']++;
        }
        int n = str.length();
        int start = -1, len = Integer.MAX_VALUE;
        for(int left = 0, right = 0; right < n; right++) {
            freRunning[str.charAt(right) - 'a']++;
            while (isGood(frePtr, freRunning)) {
                int currLength = right - left + 1;
                if(currLength < len) {
                    len = currLength;
                    start = left;
                }
                freRunning[str.charAt(left) - 'a']--;
                left++;
            }
        }
        if(start == -1) {
            System.out.println(-1);
        } else {
            System.out.println(str.substring(start, start + len));
        }

    }
}