#include <bits/stdc++.h>
using namespace std;
template<typename T>
inline void maximize(T&x, T y) {
if (x < y) x = y;
}
const int N = 3e5+7;
int n, k, a[N];
vector<long long> v;
int fa[N];
long long sum[N];
pair<int,int> range[N];
int cnt, lef, rig;
set<pair<long long,int>> comp;
long long res;
int root(int x) {
return fa[x] < 0 ? x : fa[x] = root(fa[x]);
}
void unite(int u, int v) {
if (fa[u] > fa[v]) swap(u,v);
comp.erase(make_pair(abs(sum[u]), u));
comp.erase(make_pair(abs(sum[v]), v));
fa[u] += fa[v];
fa[v] = u;
sum[u] += sum[v];
range[u].first = min(range[u].first, range[v].first);
range[u].second = max(range[u].second, range[v].second);
}
int main() {
cin.tie(nullptr)->sync_with_stdio(false);
//freopen("PHATQUA.inp", "r", stdin);
//freopen("PHATQUA.out", "w", stdout);
cin >> n >> k;
for (int i = 1; i <= n; ++i) {
cin >> a[i];
}
long long s = 0;
for (int i = 1; i <= n; ++i) {
s += a[i];
if (i==n || ((a[i]>0)^(a[i+1]>0))) {
v.push_back(s);
s = 0;
}
}
memset(fa, -1, sizeof fa);
for (int i = 0; i < (int)v.size(); ++i) {
sum[i] = v[i];
range[i] = make_pair(i,i);
}
for (int i = 0; i < (int)v.size(); ++i) {
if (v[i] > 0 || (i>0&&i+1<(int)v.size())) {
comp.emplace(abs(v[i]), i);
}
cnt += v[i] > 0;
}
lef = v[0] <= 0 ? 1 : 0;
rig = v.back() <= 0 ? (int)v.size()-2 : (int)v.size()-1;
while (cnt > k) {
int u = comp.begin()->second;
assert(u == root(u));
cnt -= sum[u] > 0;
if (range[u].first > lef) {
int v = root(range[u].first-1);
cnt -= sum[v] > 0;
unite(u, v);
}
u = root(u);
if (range[u].second < rig) {
int v = root(range[u].second+1);
cnt -= sum[v] > 0;
unite(u, v);
}
u = root(u);
if (sum[u] < 0 && (range[u].first == lef || range[u].second == rig)) {
if (range[u].first == lef) {
lef = range[u].second+1;
}
else {
rig = range[u].first-1;
}
}
else {
comp.emplace(abs(sum[u]), u);
cnt += sum[u] > 0;
}
}
for (auto p : comp) {
if (sum[p.second] > 0) {
res += sum[p.second];
}
}
cout << res;
return 0;
}
