#include <iostream>
#include <stdio.h>
using namespace std;
int a[31][2]={0};
int main()
{
    int i,j,n,w;
    scanf("%d%d",&n,&w);
    for(i=1;i<=n;i++)
    {
        int come;
        scanf("%d",&come);come--;
        for(j=w-1;j>=0;j--) 
        a[j][come]=max(a[j][come]+1,a[j+1][(come+1)%2]+1);
        a[w][come]++;
    }
    printf("%d\n",max(a[0][0],a[0][1]));
    return 0;
}