import java.util.*;
public class Main {
public static void main (String args[]) {
Scanner sc= new Scanner(System.in);
int num= sc.nextInt();
List<Integer> list= new ArrayList<>();
while(num>0){
list.add(num%10);
num=num/10;
}
Collections.reverse(list);
int i= list.size()-1;
int min=list.size()-1;
while(i>0){
if(list.get(i)>list.get(i-1)){
break;
}
min= (list.get(i)<list.get(min)) ? i : min;
i--;
}
if(i==0){
System.out.println(-1);
return;
}
i--;
//swap
int temp= list.get(i);
list.set(i,list.get(min));
list.set(min, temp);
Collections.sort(list.subList(i+1,list.size()));
num=0;
for(int x:list){
num=num*10 + x;
}
System.out.println(num);
}
}