#include<bits/stdc++.h>
using namespace std;
#define endl '\n'
#define int long long
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n,q;
cin >> n;
int a[n+1];
int l=1,r=n,k;
cin >> k;
for(int i=1;i<=n;i++){
cin >> a[i];
}
vector<int> b;
for(int i=l;i<=r;i++){
int sum=0;
int j;
for(j=i;j<=r;j++){
if(a[i]*a[j]<0){
break;
}
sum+=a[j];
}
i=j-1;
if(sum<=0&&b.empty()){
continue;
}
b.push_back(sum);
}
if(b.empty()){
cout << 0 << endl;
return 0;
}
if(b.back()<=0){
b.pop_back();
}
int ans=0,cnt=0;
int le[b.size()],ri[b.size()];
bool del[b.size()]={false};
priority_queue<pair<int,int>,vector<pair<int,int>>,greater<pair<int,int>>> pq;
for(int i=0;i<b.size();i++){
if(b[i]>0){
cnt++;
ans+=b[i];
}
le[i]=i-1;
ri[i]=i+1;
pq.push({abs(b[i]),i});
}
if(cnt<=k){
cout << ans << endl;
return 0;
}
while(cnt>k){
int idx=pq.top().second,val=pq.top().first;
pq.pop();
if(del[idx]){
continue;
}
cnt--;
ans-=val;
int nxtle=-1,nxtri=b.size();
if(le[idx]>=0){
b[idx]+=b[le[idx]];
nxtle=le[le[idx]];
del[le[idx]]=true;
}
if(ri[idx]<b.size()){
b[idx]+=b[ri[idx]];
nxtri=ri[ri[idx]];
del[ri[idx]]=true;
}
le[idx]=nxtle,ri[idx]=nxtri;
pq.push({abs(b[idx]),idx});
}
cout << ans << endl;
}
