maxR = 0
for n in range(1, 1000):
    b = bin(n)[2:]
    if n % 3 == 0:
        b = b.replace('0', '11')
    else:
        b = b.replace('1', '10')
    R = int(b, 2)
    if R < 161:
        maxR = max(maxR, R)
print(maxR)