#include <bits/stdc++.h>

#define endl '\n'
#define TRACE(x) cerr << #x << " = " << x << endl
#define SZ(x) ((int)x.size())
#define ALL(x) x.begin(), x.end()
#define pb push_back
#define eb emplace_back
#define L_B lower_bound
#define U_B upper_bound
//#define LOCAL

using namespace std;
template<class T, class T1> inline bool chkmax(T &x, const T1 &y) { return x < y ? x = y, true : false; }
template<class T, class T1> inline bool chkmin(T &x, const T1 &y) { return x > y ? x = y, true : false; }

const int MAXN = (int)1e5;

int n, k;
int a[MAXN];

void read() {
    cin >> n >> k;
    for (int i = 0; i < n; i++) cin >> a[i];
}

int nxt[MAXN];

void solve() {
    int uk = n - 1;
    for (int i = n - 1; i >= 0; i--) {
        if (!a[i]) uk = i;
        else nxt[i] = uk;
    }
    int ans = 0;
    for (int i = 0; i < n; i++) {
        if (!a[i]) continue;
        if (i && nxt[i] == nxt[i - 1]) continue;
        int curr = a[i], zeros = 0, pr = a[i];
        for (int j = i + 1; j < n; j++) {
            if (!a[j]) {
                zeros++;
                if (zeros > k) break;
                continue;
            }
            int now = max(a[j], pr + a[j]);
            chkmax(curr, now);
            chkmax(ans, curr);
            pr = now;
        }
    }
    cout << ans << endl;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    #ifndef LOCAL
    freopen("krasi.in", "rt", stdin);
    freopen("krasi.out", "wt", stdout);
    #endif // LOCAL

    read();
    solve();

    return EXIT_SUCCESS;
}