#include<bits/stdc++.h>
using namespace std;
int ans(int n,vector&arr,int k){
if(n==0){
return 0;
}
int l = 0;
int count_0 = 0;
int maximum = 0;
for(int i=0;i<n;i++){
if(arr[i]==0){
count_0++;
}
while(count_0>k){
if(arr[l]==0){
count_0--;
l++;
}
}
maximum = max(maximum,i-l+1);
}
return maximum;
}
int main() {
int n;
cin>>n;
int k;
cin>>k;
vectorarr;
for(int i=0;i<n;i++){
int x;
cin>>x;
arr.push_back(x);
}
cout << ans(n,arr,k) << endl;
}