l = input()
x = 0
if l.count(max(l)) == 1:
    x = 1
m = l.rfind(sorted(set(l[x:]))[-1])
l = list(l)
for i in range(len(l)):
    if l[i] != max(l):
        l[i],l[m] = l[m],l[i]
        break
print(''.join(l))