N = list(input())
L = len(N)

ans = int(''.join(N))
for i in range(L):
    for j in range(i + 1, L):
        # N[i], N[j] 入れ替え
        N2 = N[:]
        N2[i], N2[j] = N2[j], N2[i]
        sub = int(''.join(N2))
        ans = max(ans, sub)
print(ans)