x=list(input())
b=""
for i in x:
    b+=i
b=int(b)
x.sort(reverse=True)
x[len(x)-1],x[len(x)-2]=x[len(x)-2],x[len(x)-1]
if x[0]=="0":
    exit(print(-1))
a=""
for i in x:
    a+=i

if int(a)==b:
    exit(print(-1))

print(int(a))