#pragma GCC optimize("Ofast") #include <iostream> #include <vector> #include <algorithm> #include <map> #include <queue> #include <cstdio> #include <ctime> #include <assert.h> #include <chrono> #include <random> #include <numeric> #include <set> #include <deque> #include <stack> #include <sstream> #include <utility> #include <cstring> #include <unordered_map> #include <unordered_set> #include <tuple> #include <array> #include <bitset> using namespace std; typedef long long int ll; typedef unsigned long long ull; mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count()); ll myRand(ll B) { return (ull)rng() % B; } inline double time() { return static_cast<long double>(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count()) * 1e-9; } int main(){ cin.tie(nullptr); ios::sync_with_stdio(false); int n,k; cin >> n >> k; vector<ll> a(n); for(int i=0;i<n;i++){ cin >> a[i]; } priority_queue<ll,vector<ll>,greater<ll>> pq; ll sum = 0; ll res = 0; for(int i=n-1;i>=0;i--){ if(i%2){ if(pq.size() == k-1){ res = max(res,sum+a[i]); } } sum += a[i]; pq.push(a[i]); if(pq.size() > k-1){ sum -= pq.top(); pq.pop(); } } cout << res << endl; }