#include <bits/stdc++.h>
using namespace std;
#define long long long
const long MOD = 1e9+7, LINF = 1e18 + 1e16;
const int INF = 1e9+1;
const double EPS = 1e-10;
const int dx[4] = {-1, 0, 1, 0}, dy[4] = {0, 1, 0, -1};
const int N = 3e5+1;
class Feast {
int n, k, pre[N], nxt[N];
long ans, a[N], s[N], res[N];
priority_queue<tuple<long, int, int> > pq;
bool mark[N];
public:
void solve(istream &cin, ostream &cout) {
auto input = [&] () {
cin >> n >> k;
vector<int> org(n);
for(int i = 0; i < n; i++) cin >> org[i];
int st = 0, en = n-1;
while(st < n && org[st] <= 0) ++st;
while(en >= 0 && org[en] <= 0) --en;
if(st > en) {
return false;
}
n = 0;
for(int i = st; i <= en; i++) {
a[++n] = org[i];
}
for(int i = 1; i <= n; i++) {
s[i] = s[i-1] + a[i];
}
return true;
};
if(!input()) {
cout << 0 << endl;
return;
}
pre[0] = nxt[n] = INF;
int last = 0;
for(int i = 1; i <= n; i++) {
if(i > 1 && (a[i] > 0) != (a[i-1] > 0)) {
if(a[i-1] > 0) --k;
res[i-1] = -abs(s[i-1] - s[last]);
pre[i-1] = last;
nxt[last] = i-1;
pq.emplace(res[i-1], last, i-1);
last = i-1;
}
}
--k;
res[n] = -abs(s[n] - s[last]);
pre[n] = last;
nxt[last] = n;
pq.emplace(res[n], last, n);
while(!pq.empty() && k < 0) {
long cost;
int l, r;
tie(cost, l, r) = pq.top();
pq.pop();
if(mark[r] || mark[l] || cost != res[r]) continue;
++k;
ans += res[r];
mark[r] = mark[l] = true; // need to set mark for both l, r, as we need to prevent segments from being adjacent to each other
int ll = pre[l], rr = nxt[r];
if(ll < rr && ll >= 0 && rr <= n) {
pre[rr] = ll, nxt[ll] = rr;
res[rr] = res[rr] + res[l] - res[r];
res[r] = -LINF;
}
if(ll < rr && ll >= 0 && rr <= n && !mark[ll] && !mark[rr]) {
pq.emplace(res[rr], ll, rr);
}
}
for(int i = 1; i <= n; i++) if(a[i] > 0) ans += a[i];
cout << ans << endl;
}
};
class Solver {
public:
void solve(std::istream& in, std::ostream& out) {
Feast *obj = new Feast();
obj->solve(in, out);
delete obj;
}
};
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
Solver solver;
std::istream& in(std::cin);
std::ostream& out(std::cout);
solver.solve(in, out);
return 0;
}
