#include <bits/stdc++.h>
using namespace std;
const int LOG = 18;
int main(){
  int N, K;
  cin >> N >> K;
  vector<int> A(N * 3);
  for (int i = 0; i < N; i++){
    cin >> A[i];
    A[N + i] = A[i];
    A[N * 2 + i] = A[i];
  }
  vector<long long> S(N * 3 + 1);
  S[0] = 0;
  for (int i = 0; i < N * 3; i++){
    S[i + 1] = S[i] + A[i];
  }
  long long tv = 0;
  long long fv = S[N] + 1;
  while (fv - tv > 1){
    long long mid = (tv + fv) / 2;
    vector<int> next(N * 3, N * 3 - 1);
    for (int i = 0; i < N * 2; i++){
      next[i] = lower_bound(S.begin(), S.end(), S[i] + mid) - S.begin();
    }
    vector<vector<int>> d(LOG, vector<int>(N * 3));
    for (int i = 0; i < N * 3; i++){
      d[0][i] = next[i];
    }
    for (int i = 1; i < LOG; i++){
      for (int j = 0; j < N * 3; j++){
        d[i][j] = d[i - 1][d[i - 1][j]];
      }
    }
    bool ok = false;
    for (int i = 0; i < N; i++){
      int curr = i;
      for (int j = 0; j < LOG; j++){
        if (K >> j & 1){
          curr = d[j][curr];
        }
      }
      if (curr <= N + i){
        ok = true;
      }
    }
    if (ok){
      tv = mid;
    } else {
      fv = mid;
    }
  }
  cout << tv << endl;
}