#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cmath>
#define min(a,b) ((a)<=(b)?(a):(b))
using namespace std;
int n,m,w[2510];
int q[2510],a[2510][2]={{0}};
int main()
{
	freopen ("orz.in","r",stdin);
	freopen ("orz.out","w",stdout);
	scanf("%d%d",&n,&m);
	for (int i=1;i<=n;i++)
	{
		scanf("%d",&w[i]);
		if (w[i]==1)
		{
			a[i][0]=a[i-1][0]+1;
			a[i][1]=a[i-1][1];
		}
		else
		{
			a[i][1]=a[i-1][1]+1;
			a[i][0]=a[i-1][0];
		}
	}
	for (int i=1;i<=n;i++)
	{
		if (a[i][0]==0||a[i][1]==0)
		{
			q[i]=0;
		}
		else
		{
			int temp=0;
			if (abs((double)a[i][0]-a[i][1])>m)
			{
				temp=abs((double)a[i][0]-a[i][1])-m;
			}
			q[i]=temp;
		}
	}
	for (int i=1;i<=n;i++)
	{
		for (int k=1;k<=i;k++)
		{
			int temp=0;
			if (abs((double)a[i][0]-a[i][1])>m)
			{
				temp=abs((double)a[i][0]-a[i][1])-m;
			}
			q[i]=min(q[i],q[i-k]+temp);
		}
	}
	cout<<q[n];
	return 0;
}