#include <bits/stdc++.h>
using namespace std;
const int N = 1000005;

int n , k;
bool a[ N ]; 

signed main()
{
	cin >> n >> k;
	for( int i = 1 ; i <= n ; i ++ )
		cin >> a[ i ];
	
	int l = 1 , r = 0 , cnt = 0 , ans = INT_MIN;
	while( l <= n )
	{
		while( r < n && cnt + ( ! a[ r + 1 ] ) <= k )
			cnt += ( ! a[ ++ r ] );
		
		ans = max( ans , r - l + 1 );
		cnt -= ( ! a[ l ++ ] );
	}
	
	cout << ans;
	return 0;
}

··· #include <bits/stdc++.h> using namespace std; const int N = 1000005;

int n , k; bool a[ N ];

signed main() { cin >> n >> k; for( int i = 1 ; i <= n ; i ++ ) cin >> a[ i ];

int l = 1 , r = 0 , cnt = 0 , ans = INT_MIN;
while( l <= n )
{
	while( r < n && cnt + ( ! a[ r + 1 ] ) <= k )
		cnt += ( ! a[ ++ r ] );
	
	ans = max( ans , r - l + 1 );
	cnt -= ( ! a[ l ++ ] );
}

cout << ans;
return 0;

} ···