#include <bits/stdc++.h>
using namespace std;
#define ar array
#define ll long long
const int MAX_N = 3e5 + 1;
const int MOD = 1e9 + 7;
const int INF = 1e9;
const ll LINF = 1e18;
struct block {
int l, r;
ll sum;
} b[MAX_N];
int num = 0;
void solve() {
int n, k; cin >> n >> k;
vector<int> a(n);
for (int &x : a) cin >> x;
for (int i = 0; i < n; i++) {
b[num] = {num - 1, num + 1, 0};
int j = i;
while (j < n && (ll)a[i] * a[j] >= 0) b[num].sum += a[j++];
i = j - 1;
if (!(b[num].sum <= 0 && num == 0)) num++;
}
if (num > 0 && b[num - 1].sum <= 0) num--;
if (num == 0) {
cout << 0 << "\n";
return;
}
b[0].l = b[num - 1].r = -1;
int cnt = num / 2 + 1;
priority_queue<ar<ll,2>, vector<ar<ll,2>>, greater<ar<ll,2>>> pq;
for (int i = 0; i < num; i++) pq.push({abs(b[i].sum), i});
vector<bool> vis(num);
while (cnt > k) {
auto [v, i] = pq.top(); pq.pop();
if (vis[i]) continue;
vis[i] = true;
cnt--;
if (b[i].l == -1) {
vis[b[i].r] = true;
b[b[b[i].r].r].l = -1;
}
else if (b[i].r == -1) {
vis[b[i].l] = true;
b[b[b[i].l].l].r = -1;
}
else {
vis[b[i].r] = vis[b[i].l] = true;
b[i].sum += b[b[i].l].sum + b[b[i].r].sum;
if (b[b[i].l].l != -1) b[b[b[i].l].l].r = i;
if (b[b[i].r].r != -1) b[b[b[i].r].r].l = i;
b[i].l = b[b[i].l].l;
b[i].r = b[b[i].r].r;
vis[i] = 0;
pq.push({abs(b[i].sum), i});
}
}
ll ans = 0;
for (int i = 0; i < num; i++) {
if (vis[i] || b[i].sum <= 0) continue;
ans += b[i].sum;
}
cout << ans << "\n";
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
// freopen("input.txt", "r", stdin);
// freopen("output.txt", "w", stdout);
int tc = 1;
// cin >> tc;
for (int t = 1; t <= tc; t++) {
// cout << "Case #" << t << ": ";
solve();
}
}
