#include<stdio.h>
#define min(a,b) a<b?a:b

int n,m,a[2501],ans[2501];

int abs(int k)
{
	if(k<0)
		return -k;
	else
		return k;
}

int main()
{
	freopen("orz.in","r",stdin);
	freopen("orz.out","w",stdout);
	int i,j;
	scanf("%d%d",&n,&m);
	for(i=1;i<=n;i++)
	{
		scanf("%d",&j);
		a[i]=a[i-1];
		if(j==1)
		{
			a[i]++;
		}
	}
	for(i=1;i<=n;i++)
	{
		ans[i]=100000000;
		for(j=i;j>0;j--)
		{
			if((abs(a[i]-a[i-j]-(j-(a[i]-a[i-j])))<=m||a[i]-a[i-j]==0||a[i]-a[i-j]==j)&&ans[i-j]!=100000000)
			{
				ans[i]=min(ans[i],ans[i-j]+1);
			}
		}
	}
	printf("%d\n",ans[n]);
	return 0;
}