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