S=list(input())
N=int("".join(S))
L=list()
for i in range(len(S)-1):
    for j in range(i+1,len(S)):
        A=[i for i in S]
        A[j],A[i]=A[i],A[j]
        L.append(A)
L=[int("".join(i)) for i in L]
print(max(max(L),N))