def solution(N):
prev, next = -1, -1
cnt = 0
binary_gap = 0
while N > 0:
r = N % 2
N = (N - r) / 2
if r == 1:
prev = next
next = cnt
if prev >= 0 and next > 0 and next - prev - 1 > binary_gap:
binary_gap = next - prev - 1
cnt += 1
return binary_gap