#include <cstdio>
#include <utility>
#include <queue>
#include <cstdlib>
using namespace std;
typedef pair<int,int> ii;
typedef pair<long long,ii> iii;
int n,m,pos;
long long t,total;
int p[300005];
int r[300005];
iii node[300005];
priority_queue<iii, vector<iii>, greater<iii> > pq;
int parent(int i){return (p[i]==i)?i: p[i]=parent(p[i]);}
void unions(int i,int j){ //update node
i=parent(i),j=parent(j);
if (i>j) swap(i,j);
if (r[i]>r[j]){
p[j]=i;
node[i]=iii (node[i].first+node[j].first, ii(node[i].second.first,node[j].second.second));
}
else{
p[i]=j;
if (r[i]==r[j]) r[j]++;
node[j]=iii (node[i].first+node[j].first, ii(node[i].second.first,node[j].second.second));
}
}
void init(){
for (int x=0;x<300005;x++){
p[x]=x;
r[x]=0;
}
}
int main(){
//freopen("input.txt","r",stdin);
scanf("%d%d",&n,&m);
init();
for (int x=0;x<n;x++){
scanf("%lld",&t);
node[x]=iii(t, ii(x,x));
}
for (int x=1;x<n;x++){
if ( node[parent(x)].first==0 || (node[parent(x-1)].first^node[parent(x)].first)>=0 ){
unions(x-1,x);
}
}
for (int x=0;x<n;){
x=parent(x);
if ( !( (node[x].second.first==0 || node[x].second.second==n-1)&& node[x].first<0) )pq.push(iii(llabs(node[x].first),node[x].second));
if (node[x].first>0) pos++,total+=node[x].first;
x=node[x].second.second+1;
}
//printf("%d %lld\n",pos,total);
int s,e;
long long v;
while (pos>m){
v=pq.top().first,s=pq.top().second.first,e=pq.top().second.second,pq.pop();
if (node[parent(s)].second!=ii(s,e) ) continue;
//printf("%d %d\n",s,e);
pos--;
total-=v;
if (s!=0){
unions(s,s-1);
}
if (e!=n-1){
unions(e,e+1);
}
if ( !( (node[parent(s)].second.first==0 || node[parent(s)].second.second==n-1)&& node[parent(s)].first<0) ) pq.push(iii(abs(node[parent(s)].first),node[parent(s)].second));
}
/*for (int x=0;x<n;){
x=parent(x);
printf("%lld %d %d\n",node[x].first,node[x].second.first,node[x].second.second);
x=node[x].second.second+1;
}*/
printf("%lld\n",total);
}
