N people are arranged in a row from left to right.

You are given a string S of length N consisting of `0` and `1`, and a positive integer K.

The i-th person from the left is standing on feet if the i-th character of S is `0`, and standing on hands if that character is `1`.

You will give the following direction at most K times (possibly zero):

Direction: Choose integers l and r satisfying 1 \leq l \leq r \leq N, and flip the l-th, (l+1)-th, ..., and r-th persons. That is, for each i = l, l+1, ..., r, the i-th person from the left now stands on hands if he/she was standing on feet, and stands on feet if he/she was standing on hands.

Find the maximum possible number of consecutive people standing on hands after at most K directions.

Constraints

* N is an integer satisfying 1 \leq N \leq 10^5.
* K is an integer satisfying 1 \leq K \leq 10^5.
* The length of the string S is N.
* Each character of the string S is `0` or `1`.

Input

Input is given from Standard Input in the following format:


N K
S


Output

Print the maximum possible number of consecutive people standing on hands after at most K directions.

Examples

Input

5 1
00010


Output

4


Input

14 2
11101010110011


Output

8


Input

1 1
1


Output

1
#include <bits/stdc++.h>

using namespace std;

int a[111111];
int main() {
	int n, k, m = 0;
	string s;
	cin >> n >> k >> s;
	s += '1';
	for (int i = 0; i < n; i++) {
		a[i + 1] = a[i];
		if (s[i] == '0' &&s[i + 1] == '1')
			a[i + 1]++;
	}
	for (int l = 0, r = 1; r <= n;) {
		if (a[r] - a[l] > k) l++;
		else {
			if (r == n || s[r - 1] == '1')
				m = max(m, r - l);
			r++;
		}
	}
	cout << m << endl;
	return 0;
}
