#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef pair<int, int> PII;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, k;
    cin >> n >> k;
    vector<PII> a(n + 1);
    for (int i = 1; i <= n; i++) {
        cin >> a[i].first;
        a[i].second = i;
    }
    a[1] = {0, 1};
    sort(a.begin() + 1, a.end(), [&](PII a, PII b){
        if (a.first != b.first) return a.first > b.first;
        return a.second < b.second;
    });
    ll sum = 0;
    set<int> s;
    for (int i = 1; i <= k; i++) {
        sum += a[i].first;
        s.insert(a[i].second);
    }
    if (*s.begin() % 2 == 0) {
        cout << sum << '\n';
    } else {
        auto it = next(s.begin());
        int x = n + 1;
        if (it != s.end()) {
            x = *it;
        }
        int mx = 0;
        for (int i = 1; i <= n; i++) {
            if (a[i].second % 2 == 0 and a[i].second < x) {
                mx = max(mx, a[i].first);
            } 
            if (a[i].second == *s.begin()) {
                sum -= a[i].first;
            }
        }
        sum += mx;
        cout << sum << '\n';
    }
    return 0;
}