#include <bits/stdc++.h>
using namespace std;
long long prefsum(long long pref[],long long s, long long e){
long long ans = pref[e];
if(s>e){
return 0LL;
}
if(s){
s--;
ans-=pref[s];
}
return ans;
}
signed main(){
ios::sync_with_stdio(0);
cin.tie(0);
long long n,k;
cin >> n >> k;
vector<long long> arr(n);
set<array<long long,2>>rangs;
long long pref[n];
for(long long i = 0;i<n;i++){
cin >> arr[i];
if(arr[i]>0){
rangs.insert({i,i});
}
}
if(rangs.size()==0){
cout << 0;
return 0;
}
pref[0]=arr[0];
for(long long i = 1;i<n;i++){
pref[i]=pref[i-1]+arr[i];
}
priority_queue<array<long long,3>>joins;
set<array<long long,2>>::iterator it = rangs.begin();
long long las = (*it)[1];
it++;
while(it!=rangs.end()){
joins.push({prefsum(pref,las+1,(*it)[0]-1),las,(*it)[0]});
//cout <<"adding to joins: "<< prefsum(pref,las+1,(*it)[0]-1) << " " << las << " " << (*it)[0] << "\n";
las=(*it)[1];
it++;
}
set<array<long long,3>>rangsums;
for(array<long long,2> a : rangs){
rangsums.insert({prefsum(pref,a[0],a[1]),a[0],a[1]});
//cout << "adding to rangsums: " << prefsum(pref,a[0],a[1]) << " " << a[0]<< " " <<a[1] << "\n";
}
while(rangsums.size()>k){
rangsums.erase(rangsums.begin());
}
long long ans = 0;
long long sum = 0;
for(array<long long,3>a : rangsums){
sum+=a[0];
}
ans=max(ans,sum);
while(joins.size()){
array<long long,3>curr = joins.top();
assert(curr[0]<=0);
joins.pop();
set<array<long long,2>>::iterator it = rangs.lower_bound({curr[2],-1});
assert(it!=rangs.end());
assert(it!=rangs.end());
array<long long,2>up = *it;
assert(it!=rangs.begin());
it--;
assert(it!=rangs.end());
array<long long,2>down = *it;
assert(curr[2]==up[0]);
assert(curr[1]==down[1]);
rangs.erase(up);
rangs.erase(down);
//cout << "finding: " << prefsum(pref,down[0],down[1]) << " " << down[0] << " " << down[1] << "\n";
set<array<long long,3>>::iterator c = rangsums.find({prefsum(pref,down[0],down[1]),down[0],down[1]});
if(c!=rangsums.end()){
rangsums.erase(c);
// cout << "erased: " << prefsum(pref,down[0],down[1]) << " " << down[0] << " " << down[1] << "\n";
sum-=prefsum(pref,down[0],down[1]);
}
//cout << "finding: " << prefsum(pref,up[0],up[1]) << " " << up[0] << " " << up[1] << "\n";
c = rangsums.find({prefsum(pref,up[0],up[1]),up[0],up[1]});
if(c!=rangsums.end()){
rangsums.erase(c);
// cout << "erased: " << prefsum(pref,up[0],up[1]) << " " << up[0] << " " << up[1] << "\n";
sum-=prefsum(pref,up[0],up[1]);
}
rangs.insert({down[0],up[1]});
rangsums.insert({prefsum(pref,down[0],up[1]),down[0],up[1]});
//cout << "adding: " << prefsum(pref,down[0],up[1]) << " " << down[0] << " " << up[1] << "\n";
sum+=prefsum(pref,down[0],up[1]);
while(rangsums.size()>k){
array<long long,3>curr = *rangsums.begin();
sum-=curr[0];
//cout << "erased: " << curr[0] << " " << curr[1] << " " << curr[2] << "\n";
rangsums.erase(rangsums.begin());
}
ans=max(ans,sum);
}
assert(rangs.size()==1);
cout << ans;
return 0;
}
