#include<cstdio>
#include<cstring>
#include<algorithm>
#include<vector>
using namespace std;
const int MAXN=1222;
int dp[4][40][MAXN], ap[MAXN];
int main()
{
    int t, w, i, j, k, p;
    while(scanf("%d%d",&t,&w)!=EOF)
    {
        memset(dp,0,sizeof(dp));
        for(i=1; i<=t; i++)
        {
            scanf("%d",&ap[i]);
        }
        for(i=1; i<=t; i++)
        {
            for(j=1; j<=2; j++)
            {
                if(j==1) p=2;
                else p=1;
                for(k=0; k<=t&&k<=w; k++)
                {
                    if(j==ap[i])
                    {
                        dp[j][k][i]=max(dp[j][k][i-1]+1,dp[j][k][i]);
                        if(k<w) dp[j][k+1][i]=max(dp[p][k][i-1]+1,dp[j][k+1][i]);
                    }
                    else
                    {
                        dp[j][k][i]=max(dp[j][k][i-1],dp[j][k][i]);
                        if(k<w) dp[j][k+1][i]=max(dp[p][k][i-1],dp[j][k+1][i]);
                    }
                }
            }
        }
        int solv=0;
        for(i=1; i<=2; i++)
            for(j=0; j<=w; j++)
                if(dp[i][j][t]>solv) solv=dp[i][j][t];
        printf("%d\n",solv);
    }
    return 0;
}