最长全1串
n, k = list(map(int,input().split()))
arr = list(map(int,input().split()))
#print(arr) # must list in py3
i, j = 0,0
length =0
while j<len(arr):
if arr[j] == 1:
j+=1
elif k >0:
k-=1
j+=1
else:
length =max(j-i,length) #length!
while i<j and arr[i] ==1:
i+=1
i+=1# i +1
j+=1
length =max(j-i,length)
print(length)
