[CodeForces-676C] 尺取法

C. Vasya and String

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

High school student Vasya got a string of length n as a birthday present. This string consists of letters 'a' and 'b' only. Vasya denotesbeauty of the string as the maximum length of asubstring (consecutive subsequence) consisting of equal letters.

Vasya can change no more than k characters of the original string. What is the maximum beauty of the string he can achieve?

Input

The first line of the input contains two integers n andk (1 ≤ n ≤ 100 000, 0 ≤ k ≤ n) — the length of the string and the maximum number of characters to change.

The second line contains the string, consisting of letters 'a' and 'b' only.

Output

Print the only integer — the maximum beauty of the string Vasya can achieve by changing no more thank characters.

Examples

Input

4 2abba

Output

4

Input

8 1aabaabaa

Output

5

Note

In the first sample, Vasya can obtain both strings "aaaa" and "bbbb".

In the second sample, the optimal answer is obtained with the string "aaaaabaa" or with the string "aabaaaaa".

题目的意思就是 首先串中只有a,b两个字符；改变k个a变成的串中连续的b有多长，或者 改变k个b变成的串中连续的a有多长，两者取最大的 长度 输出

#include <bits/stdc++.h>using namespace std;const int MAXN = 100000+5;int n, k;char s[MAXN];int cal(char ch) {int l = 0, r = 0, ans = 0;int sum = 0;//当前已更改的字符个数while (l < n && r < n) {while ((sum < k || s[r] == ch) && r < n) {if (s[r] != ch) {sum++;}r++;}ans = max(ans, r-l);while (l <= r && s[l] == ch) {l++;}l++;sum--;}return ans;}int main(){while (~scanf("%d %d", &n, &k)) {scanf("%s", s);printf("%d\n", max(cal('a'), cal('b')));}return 0;}