Problem:
Score : 400 points

Problem Statement

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.

Sample Input 1

5 1
00010

Sample Output 1

4

We can have four consecutive people standing on hands, which is the maximum result, by giving the following direction:

Give the direction with l = 1, r = 3, which flips the first, second and third persons from the left.

Sample Input 2

14 2
11101010110011

Sample Output 2

8

Sample Input 3

1 1
1

Sample Output 3

1

No directions are necessary.

Solution in C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>
int main()
{
	char S[100000];
	int N,K,i,x=0,z,tag=0,sign=0;
	scanf("%d %d",&N,&K);
	getchar();
	gets(S);
	if(K>1)
	{
		for(i=0;S[i+1]!='\0';i++)
		{
			for(z=1,x=i;z<K;z++,x++)
			{		
				if(S[x]==S[x+1])
					{tag=1;break;}
				else
				{tag=0;}
			}
				if(tag==0)
					sign++;
		}
		printf("%d\n",sign);
	}
	else
	{
		for(i=0;i<N;i++)
		{
			if(S[i]=='0')
				sign++;
			else
				x++;
		}
		if(sign>x)
			printf("%d\n",sign);
		else
			printf("%d\n",x);
	}
	return 0;
}