N = input()
ln = len(N)
n = int(N)

ANS = int(N)
for i in range(ln-1):
    for j in range(i+1, ln):
        if i != j:
            p = ''
            for k in range(ln):
                if k == i:
                    p += N[j]
                elif k == j:
                    p += N[i]
                else:
                    p += N[k]
            ANS = max(ANS, int(p))

print(ANS)