X=str(input())
x=[]
y=[]
for i in range(len(X)):
    x.append(X[i])
x.sort(reverse=True)
x[-1],x[-2]=x[-2],x[-1]
if x[0] == "0":
    print("-1")
elif x[-2]==x[-1]:
    print("-1")
else:
    s="".join(x)
    print(s)