s = raw_input()
for d in range(1,len(s)):
    t = s[0:d]
    u = s[d:]
    if min(t) < max(u):
        p = s.find(min(t))
        q = s.rfind(max(u))
        l = list(s)
        l[p] = s[q]
        l[q] = s[p]
        s = ''.join(l)
        break
print s