X = input()
l = list(X)
f = 0

ll = list(map(int,l))
ll.sort()
# ll.reverse()

for i in range(len(l)-1):
    if ll[i] != ll[i+1]:
        ll[i],ll[i+1] = ll[i+1], ll[i]
        break
else:
    f = 1 

if f == 0:
    ll.reverse()
    ans = "".join(map(str,ll))
    if len(ans) == len(str(int(ans))):
        print(ans)
    else:
        print(-1)
else:
    print(-1)