7

for i in range(1, 1001):
    a = i
    a_bin = bin(int(a))[2:]
    sum_a_bin = sum(list(map(int, map(lambda x: x + ' ', a_bin))))
    a_bin += str(sum_a_bin % 2)
    sum_a_bin = sum(list(map(int, map(lambda x: x + ' ', a_bin))))
    a_bin += str(sum_a_bin % 2)
    if int(a_bin, 2) > 43:
        print(int(a_bin, 2))
        break