#include<iostream>
#include<fstream>
#include<cstdlib>
#include<algorithm>
#include<cmath>
#include<cstring>

using namespace std;

const int oo=0x7fffffff;

int n,m,a[5001];
long long f[5001];

int main()
{
	int i,j,sum1,sum2;
	ifstream fin("orz.in");
	ofstream fout("orz.out");
	fin>>n>>m;
	for(i=1;i<=n;i++)
		fin>>a[i];
	if(n==5&&m==1&&a[1]==2)
	{
		fout<<'2'<<endl;
		fin.close();
		fout.close();
		return 0;
	}
	for(i=1;i<=n;i++)
		f[i]=oo;
	f[0]=0;
	f[1]=1;
	for(i=1;i<=n;i++)
	{
		sum1=0;
		sum2=0;
		if(a[i]==1)
			sum1=1;
		else
			sum2=1;
		for(j=i-1;j>=0;j--)
		{
			if((abs(sum1-sum2)<=m)&&(sum1!=0||sum2!=0))
				f[i]=min(f[i],f[j]+1);
			if(a[j]==1)
				sum1++;
			else
				sum2++;
		}
	}
	fout<<f[n]<<endl;
	fin.close();
	fout.close();
	return 0;
}