import itertools,copy
N = [int(i) for i in list(input())]
C = itertools.combinations(range(len(N)),2)
ans = 0
cur = 0
for n in N:
    ans *= 10
    ans += n

for a,b in C:
    NewN = copy.deepcopy(N)
    NewN[a],NewN[b] = NewN[b],NewN[a]
    cur = 0
    for n in NewN:
        cur *= 10
        cur += n
    ans = max(cur,ans)
print(ans)