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

using i32 = int;
using i64 = long long;
using i128 = __int128_t;
using f64 = double;
using p2 = pair<i64, i64>;
using p3 = tuple<i64, i64, i64>;

void _main();
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(18);
  _main();
}

void _main() {
  i64 n, m;
  cin >> n >> m;
  priority_queue<i64, vector<i64>, greater<i64>> que;
  for (i64 i = 0; i < m; i++) que.push(0);
  i64 ans = 0;
  for (i64 i = 0; i < n; i++) {
    i64 x = que.top(); que.pop();
    i64 t;
    cin >> t;
    que.push(x + t);
    ans = max(ans, x + t);
  }
  cout << ans << "\n";
}