#include<bits/stdc++.h>
#define mp make_pair
#define fi first
#define se second
#define ii pair<int, int>
#define iii pair<ii, int>
#define ll long long
#define pb push_back
#define pli pair<ll, int>
#define all(v) (v).begin(), (v).end()
#define uniquev(v) sort(all(v)), (v).resize(unique(all(v)) - (v).begin())
#define cntbit(mask) __builtin_popcount(mask)
#define getbit(x, i) ((x >> i) & 1)
#define MASK(i) (1 << i)
#define pli pair<ll, int>
using namespace std;
template<class T1, class T2>
bool maximize(T1 &a, T2 b){if(a < b){a = b; return 1;} return 0;}
template<class T1, class T2>
bool minimize(T1 &a, T2 b){if(a > b){a = b; return 1;} return 0;}
const int N = 2005;
const int V = 3e5 + 5;
const int MOD = 1e9 + 7;
int n, k, a[V], pos;
pli sum = mp(0, 1);
set<pli> Q;
set<int> s;
ll cost[V], ans;
void solve() {
cin >> n >> k;
for(int i = 1 ; i <= n ; i++) {
cin >> a[i];
if (i == 1 || (sum.fi < 0 && a[i] < 0) || (sum.fi >= 0 && a[i] >= 0)) sum.fi += a[i];
else {
if (sum.se > 1 || sum.fi >= 0) {
cost[sum.se] = sum.fi;
if (sum.fi >= 0) pos++;
sum.fi = abs(sum.fi);
Q.insert(sum);
s.insert(sum.se);
}
sum = mp(a[i], i);
}
}
if (sum.fi >= 0) {
pos++;
cost[sum.se] = sum.fi;
Q.insert(sum);
s.insert(sum.se);
}
while((int) pos > k) {
pli x = *Q.begin();
auto u = s.lower_bound(x.se), v = u;
++v;
if (cost[x.se] < 0 && (u == s.begin() || v == s.end())) {
s.erase(u);
Q.erase(Q.begin());
continue;
}
int re[2] = {0, 0};
if (cost[x.se] >= 0) --pos;
if (u != s.begin()) {
--u;
cost[x.se] += cost[*u];
re[0] = *u;
}
if (v != s.end()) {
cost[x.se] += cost[*v];
re[1] = *v;
}
Q.erase(Q.begin());
for(int j = 0 ; j < 2 ; j++) if (re[j]) {
if (cost[re[j]] >= 0) --pos;
s.erase(re[j]);
auto it = Q.find(pli(abs(cost[re[j]]), re[j]));
if (it != Q.end()) Q.erase(it);
}
Q.insert(mp(abs(cost[x.se]), x.se));
if (cost[x.se] >= 0) ++pos;
}
while((int) Q.size()) {
pli x = *Q.begin();
Q.erase(Q.begin());
if (cost[x.se] >= 0) ans += cost[x.se];
} cout << ans;
}
int main(void) {
//freopen("task.inp", "r", stdin);
//freopen("task.out", "w", stdout);
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
int t = 1; while(t--) solve();
return 0;
}
