#ifdef ONLINE_JUDGE
#pragma GCC optimize("Ofast")
#pragma GCC target("avx2,bmi,bmi2,lzcnt")
#endif

#include <bits/extc++.h>
#include <x86intrin.h>

#ifndef DUMP
#define DUMP(...) void(0)
#endif

using namespace std;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int n, k;
  cin >> n >> k;
  vector<int64_t> pref(2 * n + 1);
  for (int i = 0; i < n; ++i) {
    int a;
    cin >> a;
    pref[i + 1] = pref[i] + a;
  }
  for (int i = n + 1; i <= 2 * n; ++i) pref[i] = pref[i - n] + pref[n];
  DUMP(pref);

  constexpr int lg = 17;
  auto check = [&](int64_t m) -> bool {
    vector to(lg, vector<int64_t>(n));
    for (int i = 0; i < n; ++i) {
      to[0][i] = i ? to[0][i - 1] : 0;
      while (pref[to[0][i]] - pref[i] < m) ++to[0][i];
    }
    for (int s = 1; s < lg; ++s)
      for (int i = 0; i < n; ++i) {
        int ni = to[s - 1][i] % n;
        to[s][i] = to[s - 1][i] + (to[s - 1][ni] - ni);
      }
    for (int i = 0; i < n; ++i) {
      int t = k;
      int64_t cur = i;
      for (int s = lg; s--;) {
        if (t < 1 << s) continue;
        t -= 1 << s;
        cur += to[s][cur % n] - cur % n;
      }
      if (cur - i <= n) return true;
    }
    return false;
  };

  int64_t ok = 1, ng = pref.back() + 1;
  while (ng - ok > 1) {
    auto mid = (ok + ng) / 2;
    (check(mid) ? ok : ng) = mid;
  }
  cout << ok << '\n';
}