def larger(x, y):
	if x > y: return x
	else: return y

N = raw_input()
max = int(N)

for i in range(0, len(N)):
	for j in range(i+1, len(N)):
		s = ''
		for k in range(0, len(N)):
			if k == i: s = s + N[j]
			elif k == j: s = s + N[i]
			else: s = s + N[k]
		max = larger(int(s), max)
print max