#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
#define int long long
int a[300005], l[300005], r[300005];
set<pair<int, int> > s;
vector<int> vec;
signed main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, k, sz, sum=0, cnt=0, ans=0;
cin >> n >> k;
for (int i=1; i<=n; i++)
{
cin >> a[i];
if ((a[i-1]>0)^(a[i]>0))
{
vec.push_back(sum);
sum=0;
}
sum+=a[i];
}
vec.push_back(sum);
if (vec[0]<=0)
vec.erase(vec.begin());
if (vec.size() && vec.back()<=0)
vec.erase(--vec.end());
sz=vec.size();
for (int i=0; i<sz; i++)
{
s.insert({abs(vec[i]), i});
l[i]=(i==0)?-1:(i-1);
r[i]=(i==sz-1)?-1:(i+1);
if (vec[i]>0)
cnt++;
}
//for (int x:vec)
// cout << x << ' ';
// cout << '\n';
while (cnt>k)
{
int ind=(*s.begin()).second, val=vec[ind], ok=1;
if (l[ind]==-1 || r[ind]==-1)
ok=0;
//cout << "ind " << ind << '\n';
s.erase({abs(vec[ind]), ind});
if (vec[ind]>0)
cnt--;
if (l[ind]!=-1)
{
if (vec[l[ind]]>0)
cnt--;
s.erase({abs(vec[l[ind]]), l[ind]});
val+=vec[l[ind]];
vec[l[ind]]=0;
l[ind]=l[l[ind]];
if (l[ind]!=-1)
r[l[ind]]=ind;
}
if (r[ind]!=-1)
{
if (vec[r[ind]]>0)
cnt--;
s.erase({abs(vec[r[ind]]), r[ind]});
val+=vec[r[ind]];
vec[r[ind]]=0;
r[ind]=r[r[ind]];
if (r[ind]!=-1)
l[r[ind]]=ind;
}
if (ok)
{
s.insert({abs(val), ind});
vec[ind]=val;
if (val>0)
cnt++;
}
else
{
int L=l[ind], R=r[ind];
if (L!=-1)
r[L]=R;
if (R!=-1)
l[R]=L;
vec[ind]=0;
}
//for (int x:vec)
// cout << x << ' ';
//cout << '\n';
}
for (int i=0; i<sz; i++)
ans+=vec[i]*(vec[i]>0);
cout << ans;
}
