#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;
template<class t> using vc = vector<t>;
template<class t> using vvc = vc<vc<t>>;
using pi = pair<int,int>;
using vi = vc<int>;
using vvi = vvc<int>;

#define rep(i,a,b) for (int i = a; i < b; i++)
#define irep(i,a,b) for (int i = a; i > b; i--)
#define print(n) cout << n << endl
#define rup(a,b) (a+b-1)/b


int main(){
    cout << fixed << setprecision(15);
    
    int N,K;
    cin >> N >> K;
    vc<ll> A(N,0);
    rep(i,0,N) cin >> A[i];
    ll ans = 0;
    multiset<ll> d;
    ll aa = 0;

    int now = 0;
    irep(i,A.size()-1,0){
        if (now <= K-1){
            now++;
            ans += A[i];
            d.insert(A[i]);
            continue;
        }
        if (i%2 == 1){
            aa = max(ans+A[i],aa);
        }
        d.insert(A[i]);
        ll b = *d.begin();
        ans += A[i] - b;
        d.erase(d.begin());
    }

    print(ans);


    
    //system("pause");
    return 0;
}