x=list(input())
if len(set(x))==1:
    exit(print(-1))

x.sort()
for i in range(len(x)-1):
    if [i]==x[i+1]:
        continue
    if i+1<len(x)-1:
        x[i],x[i+1]=x[i+1],x[i]
        print("".join(x[::-1]))
        exit()

print(-1)