#include <bits/stdc++.h>
using namespace std;
#define int long long
int arr[300001];
int a[300001];
int s[300001];
int cost[300001];
int pre[300001];
int nex[300001];
bool mark[300001];
priority_queue<tuple<int, int, int>> pq;
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
int n, k;
cin >> n >> k;
for (int i = 0; i < n; i++) {
cin >> arr[i];
}
int start = 0;
int end = n - 1;
while (start < n && arr[start] <= 0) {
start++;
}
while (end >= 0 && arr[end] <= 0) {
end--;
}
if (start > end) {
cout << 0;
return 0;
}
n = 0;
for (int i = start; i <= end; i++) {
a[++n] = arr[i];
}
for (int i = 1; i <= n; i++) {
s[i] = s[i - 1] + a[i];
}
int last = 0;
pre[0] = nex[n] = 1e9;
for (int i = 1; i <= n; i++) {
if (i > 1 && (a[i] > 0) != (a[i - 1] > 0)) {
if (a[i - 1] > 0) {
--k;
}
cost[i - 1] = -abs(s[i - 1] - s[last]);
pre[i - 1] = last;
nex[last] = i - 1;
pq.emplace(cost[i - 1], last, i - 1);
last = i - 1;
}
}
--k;
cost[n] = -abs(s[n] - s[last]);
pre[n] = last;
nex[last] = n;
pq.emplace(cost[n], last, n);
int ans = 0;
while (!pq.empty() && k < 0) {
int price, l, r;
tie(price, l, r) = pq.top();
pq.pop();
if (mark[l] || mark[r] || price != cost[r]) {
continue;
}
++k;
ans += cost[r];
mark[l] = mark[r] = true;
int ll = pre[l];
int rr = nex[r];
if (ll < rr && ll >= 0 && rr <= n) {
pre[rr] = ll;
nex[ll] = rr;
cost[rr] += cost[l] - cost[r];
cost[r] = -1e18;
}
if (ll < rr && ll >= 0 && rr <= n && !mark[ll] && !mark[rr]) {
pq.emplace(cost[rr], ll, rr);
}
}
for (int i = 1; i <= n; i++) {
if (a[i] > 0) {
ans += a[i];
}
}
cout << ans;
}
