#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define f first
#define s second
#define pb push_back
#define ep emplace
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define uniquev(v) sort(all(v)), (v).resize(unique(all(v)) - (v).begin())
#define mem(f,x) memset(f , x , sizeof(f))
#define sz(x) (ll)(x).size()
#define __lcm(a, b) (1ll * ((a) / __gcd((a), (b))) * (b))
#define mxx *max_element
#define mnn *min_element
#define cntbit(x) __builtin_popcountll(x)
#define len(x) (int)(x.length())
const int N = 3e5 + 10;
int p[N], sz[N], l[N], r[N], a[N];
ll val[N];
set <pair <ll, ll>> st;
int get(int x) {
return p[x] ? get(p[x]) : x;
}
void unite(int a, int b) {
a = get(a), b = get(b);
if (a == b)
return;
if (sz[a] < sz[b])
swap(a, b);
sz[a] += sz[b];
p[b] = a;
l[a] = min(l[a], l[b]);
r[a] = max(r[a], r[b]);
val[a] += val[b];
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, k;
cin >> n >> k;
for (int i = 1; i <= n; i++) {
cin >> a[i];
sz[i] = 1;
l[i] = r[i] = i;
}
while (a[n] <= 0 && n)
n--;
if (n == 0) {
cout << 0 << '\n';
return 0;
}
int ft = 1;
while (a[ft] <= 0)
ft++;
for (int j = ft; j <= n; j++)
a[j - ft + 1] = a[j];
for (int i = 1; i <= n; i++) {
val[i] = a[i];
}
for (int i = 1; i < n; i++) {
if (bool(a[i] >= 0) == bool(a[i + 1] >= 0))
unite(i, i + 1);
}
for (int i = 1; i <= n; i++) {
if (get(i) == i) {
st.insert({abs(val[get(i)]), i});
}
}
int ss = 1;
while (sz(st) > k * 2) {
auto it = *st.begin();
st.erase(it);
int p = get(it.s);
if (l[p] > ss) {
int x = get(l[p] - 1);
st.erase({abs(val[x]), x});
unite(p, x);
}
if (r[p] < n) {
int x = get(r[p] + 1);
st.erase({abs(val[x]), x});
unite(p, x);
}
p = get(p);
st.insert({abs(val[p]), p});
while (val[get(n)] <= 0) {
st.erase({abs(val[get(n)]), get(n)});
n = l[get(n)] - 1;
}
while (val[get(ss)] <= 0) {
st.erase({abs(val[get(ss)]), get(ss)});
ss = r[get(ss)] + 1;
}
}
ll ans = 0;
while (sz(st)) {
auto it = *st.begin();
st.erase(it);
int p = it.s;
ans += max((ll)0, val[p]);
}
cout << ans << '\n';
return 0;
}
