s=list(map(int,list(input())))
s=sorted(s)[::-1]
l=[x for x in s]
x=-1
if len(set(l))>1:
	for i in range(1,len(s)):
		if 0<l[-i]<l[-i-1]:
			l[-i],l[-i-1]=l[-i-1],l[-i]
			x=''.join(map(str,l)); break
print(x)