#include <bits/stdc++.h>
using namespace std;
using ll = long long;
struct DSU {
vector<int> e;
vector<ll> sum;
vector<int> l, r;
DSU(int n) {
e = vector<int>(n, -1);
sum = vector<ll>(n);
l = vector<int>(n);
r = vector<int>(n);
}
int get(int x) {
return e[x] < 0 ? x : e[x] = get(e[x]);
}
void unite(int x, int y) {
x = get(x);
y = get(y);
if (x == y) return; // neturetu reiket?
if (e[x] > e[y]) swap(x, y);
l[x] = min(l[x], l[y]);
r[x] = max(r[x], r[y]);
sum[x] += sum[y];
e[x] += e[y];
e[y] = x;
}
};
void chmax(ll& x, ll y) {
x = max(x, y);
}
int main() {
int N, K;
cin >> N >> K;
vector<ll> a(N);
for (int i = 0; i < N; ++i) {
cin >> a[i];
}
DSU dsu(N);
for (int i = 0; i < N; ++i) {
dsu.sum[dsu.get(i)] = a[i];
dsu.l[dsu.get(i)] = i;
dsu.r[dsu.get(i)] = i;
}
for (int i = 1; i < N; ++i) {
if (dsu.sum[dsu.get(i)] >= 0 && dsu.sum[dsu.get(i - 1)] >= 0) {
dsu.unite(i, i - 1);
} else if (dsu.sum[dsu.get(i)] <= 0 && dsu.sum[dsu.get(i - 1)] <= 0) {
dsu.unite(i, i - 1);
}
}
priority_queue<pair<ll, int>> pq;
vector<int> vis(N);
for (int i = 0; i < N; ++i) {
if (vis[dsu.get(i)]) continue;
// cout << dsu.sum[dsu.get(i)] << " ";
vis[dsu.get(i)] = 1;
pq.push({dsu.sum[dsu.get(i)], i});
}
// cout << "\n";
auto get_right = [&](int i) -> int{
i = dsu.get(i);
ll mx = dsu.sum[i];
ll tot = dsu.sum[i];
if (dsu.r[i] + 1 >= N) return -1;
int j = dsu.get(dsu.r[i] + 1);
tot += dsu.sum[j];
if (dsu.r[j] + 1 >= N) return -1;
j = dsu.r[j] + 1;
tot += dsu.sum[j];
mx = max(mx, dsu.sum[j]);
if (tot < mx) return -1;
return j;
};
auto get_left = [&](int i) -> int{
i = dsu.get(i);
ll mx = dsu.sum[i];
ll tot = dsu.sum[i];
if (dsu.l[i] - 1 < 0) return -1;
int j = dsu.get(dsu.l[i] - 1);
tot += dsu.sum[j];
if (dsu.l[j] - 1 < 0) return -1;
j = dsu.l[j] - 1;
tot += dsu.sum[j];
mx = max(mx, dsu.sum[j]);
if (tot < mx) return -1;
return j;
};
while (pq.size()) {
ll d = pq.top().first;
int i = pq.top().second;
pq.pop();
if (d <= 0) continue;
// cout << d << "\n";
bool done = false;
if (get_right(i) != -1) {
i = dsu.get(i);
// cout << i << " " << dsu.r[i] + 1 << " -> ";
dsu.unite(dsu.r[i] + 1, i);
i = dsu.get(i);
// cout << i << " " << dsu.r[i] + 1 << "\n";
dsu.unite(dsu.r[i] + 1, i);
done = true;
}
if (get_left(i) != -1) {
i = dsu.get(i);
dsu.unite(dsu.l[i] - 1, i);
i = dsu.get(i);
dsu.unite(dsu.l[i] - 1, i);
done = true;
}
if (done) {
pq.push({-dsu.sum[dsu.get(i)], i});
}
}
set<int> st;
for (int i = 0; i < N; ++i) {
int j = dsu.get(i);
if (st.count(j)) continue;
st.insert(j);
// cout << dsu.sum[j] << " ";
pq.push({dsu.sum[j], j});
}
// cout << "\n";
ll res = 0;
for (int i = 0; i < K && pq.size(); ++i) {
ll d = pq.top().first;
pq.pop();
if (d <= 0) continue;
res += d;
}
cout << res << "\n";
}
