#include <bits/stdc++.h>
#include <atcoder/all>

using namespace std;
using namespace atcoder;

using ll = long long;
using mint = modint998244353;
// using mint = modint1000000007;

template <typename T> using vec = vector<T>;
template <typename T> using pa = pair<T, T>;
template <typename T> using mipq = priority_queue<T, vec<T>, greater<T>>;

#define REP(_1, _2, _3, _4, name, ...) name
#define REP1(i, n) for (auto i = decay_t<decltype(n)>{}; (i) < (n); ++(i))
#define REP2(i, l, r) for (auto i = (l); (i) < (r); ++(i))
#define REP3(i, l, r, d) for (auto i = (l); (i) < (r); i += (d))
#define rep(...) REP(__VA_ARGS__, REP3, REP2, REP1)(__VA_ARGS__)
#define rrep(i, r, l) for (int i = (r); i >= (l); --i)
template <typename T> bool chmax(T &a, const T &b) { return (a < b ? a = b, true : false); }
template <typename T> bool chmin(T &a, const T &b) { return (a > b ? a = b, true : false); }

constexpr int INF = 1 << 30;
constexpr ll LINF = 1LL << 60;
constexpr int mov[4][2] = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};

void solve();

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(15);
    int T = 1;
    // cin >> T;
    while (T--) solve();
}

void solve() {
    int N, M;
    cin >> N >> M;
    mipq<ll> pq;
    rep(i, M) pq.push(0);

    ll ans = 0;
    rep(i, N) {
        int t;
        cin >> t;
        ll v = pq.top(); pq.pop();
        chmax(ans, v + t);
        pq.push(v + t);
    }
    cout << ans << '\n';
}