#include <bits/stdc++.h>
using namespace std;
int main(){
  int N, M;
  cin >> N >> M;
  vector<int> A(N);
  for (int i = 0; i < N; i++){
    cin >> A[i];
  }
  int tv = 0, fv = 1000000001;
  while (fv - tv > 1){
    int mid = (tv + fv) / 2;
    bool ok = true;
    vector<long long> B(N);
    for (int i = 0; i < N; i++){
      B[i] = A[i];
    }
    for (int i = 0; i < N; i++){
      if (B[i] < mid){
        ok = false;
        break;
      }
      if (i < N - 1){
        B[i + 1] += B[i] - mid;
      }
    }
    if (ok){
      tv = mid;
    } else {
      fv = mid;
    }
  }
  cout << tv / M << endl;
}