// Source: https://usaco.guide/general/io
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define eb emplace_back // faster than push_back xD
// pbds UwU
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define oset tree<ll, null_type,less<ll>, rb_tree_tag,tree_order_statistics_node_update> // use pair for ms
// my io library :D
#define m1(x) template<class T, class... U> void x(T&& a, U&&... b)
#define m2(x) (ll[]){(x forward<U>(b),0)...}
m1(pr){cout << forward<T>(a); m2(cout << " " <<); cout << "\n";}
m1(re){cin >> forward<T>(a); m2(cin >>);}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
ll n, k; re(n, k);
vector<ll> a(n);
for (ll i{}; i < n; i++) re(a[i]);
ll neg = -1;
for (ll i{}; i < (ll)n; i++) {
if (a[i] < 0) { neg = i; break; }
}
if (neg == -1) {
ll total = accumulate(a.begin(), a.end(), 0LL);
pr(total);
} else {
ll l = accumulate(a.begin(), a.begin() + neg, 0LL);
ll r = accumulate(a.begin() + neg + 1, a.end(), 0LL);
if (k != 1) pr(l + r);
else pr(max(l, r));
}
}
