#include <bits/stdc++.h>

using namespace std;
const int N = 1010, M = 35;

int n, m;
bool st[N];
int f[N][M][2];

int main() {
    cin >> n >> m;
    for (int i = 1; i <= n; i ++ ) {
        int x;
        cin >> x;
        if (x - 1) 
            st[i] = true;
    }

    f[1][0][0] = !st[1];
    f[1][1][1] = st[1];
    for (int i = 2; i <= n; i ++ ) {
        f[i][0][0] += f[i - 1][0][0] + (int)(!st[i]);
        f[i][1][1] += f[i - 1][1][1] + (int)(st[i]);
    }

    for (int i = 2; i <= n; i ++ )
        for (int j = 1; j <= min(n, m); j ++ ) {
            if(j & 1) f[i][j][1] = max(f[i][j][1], max(f[i - 1][j - 1][0], f[i - 1][j][1]) + (int)(st[i]));
            else f[i][j][0] = max(f[i][j][0], max(f[i - 1][j - 1][1], f[i - 1][j][0]) + (int)(!st[i]));
        }

    int ans = -0x3f3f3f3f;
    for (int i = 0; i <= m; i ++ )
        ans = max(f[n][i][0], f[n][i][1]);

    cout << ans << endl;

    return 0;
}