View Code of Problem 3911

import java.util.*;
public class Main {
	public static void main(String[] args) {
		Scanner in =new Scanner(System.in);
		while(in.hasNext()) {
			char[] s = in.next().toCharArray();
			char[]  t = in.next().toCharArray();
			for(int i =0;i<s.length-1;i++) {
				for(int j =0;j<s.length-1-i;j++) {
					if(s[j]>s[j+1]) {
						char temp =s[j+1];
						s[j+1]=s[j];
						s[j]=temp;
					}
				}
			}
			StringBuffer sb = new StringBuffer();
			sb.append(s);
			for(int i =0;i<t.length;i++) {
				for(int j =i;j<sb.length();j++) {
					if(sb.charAt(j)>t[i]) {
						char temp = sb.charAt(j);
						sb.deleteCharAt(j);
						sb.insert(i, temp);
					}
				}
			}
			String ss = sb.toString();
			StringBuffer sbt = new StringBuffer();
			sbt.append(t);
			String st  =sbt.toString();
			if(ss.compareTo(st)>0) {
				System.out.println(ss);
			}else {
				System.out.println(-1);
			}
		}
	}
}