#include <bits/stdc++.h>
using namespace std;
#define oo 1e15
#define fi first
#define se second
#define sp(iiii) setprecision(iiii)
#define IO ios_base::sync_with_stdio(false); cin.tie(0)
#define ms(aaaa,xxxx) memset(aaaa,xxxx,sizeof(aaaa))
#define cntbit(xxxx) __builtin_popcount(xxxx)
#define getbit(xxxx,aaaa) ((xxxx>>(aaaa-1))&1)
typedef long double ld;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<pair<int,int>,int> piii;
typedef pair<long long,long long> pll;
typedef pair<pair<long long,long long>,long long> plll;
typedef pair<pair<long long,long long>,pair<long long,long long>> pllll;
typedef pair<pair<long long,long long>,bool> pllb;
const ll base=361;
const ll mod=998244353;
const ld eps=1e-5;
const ll maxn=1e6;
struct comp{
bool operator() (pll x,pll y) {
return x.fi>y.fi;
}
};
priority_queue<pll,vector<pll>,comp> heap;
ll n,k,i,a[400009],tmp,b[400009],m,l[400009],r[400009],res,cnt,cur;
bool ok[400009];
int main(){
IO;
cin>>n>>k;
for (i=1;i<=n;i++) {
cin>>a[i];
}
for (i=1;i<=n;i++) {
if (a[i]*a[i-1]<0) {
m++;
b[m]=cur;
cur=a[i];
}
else {
cur+=a[i];
}
}
m++;
b[m]=cur;
for (i=1;i<=m;i++) {
l[i]=i+1;
r[i]=i-1;
if (b[i]>0) {
cnt++;
}
heap.push({abs(b[i]),i});
}
while (cnt>k) {
ll y=heap.top().fi;
ll x=heap.top().se;
heap.pop();
if (ok[x]) continue;
tmp=0;
if (b[x]>0) {
tmp++;
}
if (b[r[x]]>0) {
tmp++;
}
if (b[l[x]]>0) {
tmp++;
}
if (b[x]+b[l[x]]+b[r[x]]>0) {
tmp--;
}
cnt-=tmp;
ok[l[x]]=true;
ok[r[x]]=true;
b[x]=b[l[x]]+b[r[x]]+b[x];
l[x]=l[l[x]];
r[x]=r[r[x]];
heap.push({abs(b[x]),x});
}
for (i=1;i<=m;i++) {
if (!ok[i]&&b[i]>0) {
res+=b[i];
}
}
cout<<res<<'\n';
}
