#include <bits/stdc++.h>
#define int long long // 仅在需要大整数时使用，memset 数组为 0x3f 时去掉
#define INF 0x3f3f3f3f
#define PII pair<int, int>
#define ULL unsigned long long
#define PIII tuple<int, int, int>
#define all(v) v.begin(), v.end()
#define debug(a) cout << #a << " = " << a << endl;
using namespace std;
constexpr int N = 1 * 1e6 + 10, M = 5 * 1e3 + 10;


void solve() {
    int n, k;
    cin >> n >> k;
    auto arr = vector<int>(n);
    for (auto &x : arr) cin >> x;
    sort(all(arr));
    int ans = 1e18 + 10;
    for (int l = n - k * 2, r = n - 1, cnt = 0; cnt < k ; l ++, r --, cnt ++) {
        ans = min(arr[l] + arr[r], ans);
    }
    cout << ans << '\n';
}

signed main() {
    ios::sync_with_stdio(0); cin.tie(nullptr), cout.tie(nullptr);
    int _ = 1;
    // cin >> _;
    while (_--) {
        solve();
    }
    return 0;
}

/**
 *    author: Nijika_jia
 *    description: C++17 Algorithm Template for Competitive Programming
 */