import itertools
x = list(input())
ans = []
for l in itertools.permutations(x):
    x = ''.join(i for i in l)
    if x[0]=='0':
        continue
    else:
        x = int(x)
        if x not in ans:
            ans.append(x)
print(sorted(ans)[-2] if len(ans)!=1 else -1)