#include 
#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;
const int maxn = 505;
int n, k;
vector v(maxn), rev(maxn);
int one[maxn], two[maxn];
int query(int i, int j, char c) {
    if(i == 0) {
        if(c == '1') {
            return one[j];
        }
        else {
            return two[j];
        }
    }
    if(i > j) {
        return 0;
    }
    if(c == '1') {
        return one[j] - one[i - 1];
    }
    return two[j] - two[i - 1];
}
int main() {
    ios_base::sync_with_stdio(false);
//    ifstream cin("in.txt");
    cin >> n >> k;
     
    int o = 0, t = 0;
    for(int i = 0; i < n; i++) {
        cin >> v[i];
        if(v[i] == 1) {
            o++;
        }
        else {
            t++;
        }
        one[i] = o;
        two[i] = t;
    }
    int ret = 0;
    if(k <= 2) {
        for(int i = 0; i < n; i++) {
            for(int j = i + 1; j < n; j++) {
                for(int x = j; x > i; x--) {
                    ret = max(ret, query(0, i - 1, '1') + query(x, j, '1') + query(i, x - 1, '2') + query(j + 1, n - 1, '2'));
                }
            }
        }
        cout << ret << endl;
        return 0;
    }