#include <bits/stdc++.h>
using namespace std;
#define int long long
struct Node{
Node *p,*child;
int val;
Node(int ival): p(nullptr),child(nullptr),val(ival) {};
};
signed main(){
cin.tie(0);
ios_base::sync_with_stdio(0);
//start here
int N,K;cin >> N >> K;
vector<int> v;
int prev = 0;
for(int i = 0;i < N;i++){
int cur;cin >> cur;
if(cur*prev < 0){
if(!v.empty() || prev > 0){
v.push_back(prev);
}
prev = cur;
}else{
prev += cur;
}
}
v.push_back(prev);
if(v.size() >= 1 && v.back() < 0)v.pop_back();
// for(auto i:v)cout << i << " ";cout << endl;
// greedy
N = v.size();
set<pair<int,Node*>> s;
int ans = 0;
int used = 0;
vector<Node*> link;
for(int i = 0;i < N;i++){
link.push_back(new Node(v[i]));
if(i != 0){
link[i]->p = link[i-1];
link[i-1]->child = link[i];
}
if(v[i] > 0){
used++;
ans += v[i];
}
s.insert({abs(v[i]),link[i]});
}
while(used > K){
ans -= s.begin()->first;
Node* cur = s.begin()->second;
s.erase(s.begin());
if(cur->p != nullptr){
cur->val += cur->p->val;
s.erase({abs(cur->p->val),cur->p});
cur->p = cur->p->p;
if(cur->p != nullptr)cur->p->child = cur;
}
if(cur->child != nullptr){
cur->val+cur->child->val;
s.erase({abs(cur->child->val),cur->p});
cur->child = cur->child->child;
if(cur->child != nullptr)cur->child->p = cur;
}
s.insert({cur->val,cur});
used--;
}
cout << ans;
}
