/* -*- coding: utf-8 -*-
 *
 * 1808.cc:  No.1808 Fullgold Alchemist - yukicoder
 */

#include<cstdio>
#include<algorithm>
 
using namespace std;

/* constant */

const int MAX_N = 200000;

/* typedef */

typedef long long ll;

/* global variables */

int as[MAX_N];

/* subroutines */

bool check(int n, int x) {
  ll sum = 0;
  for (int i = 0; i < n; i++) {
    if (x > as[i] + sum) return false;
    sum += as[i] - x;
  }
  return true;
}

/* main */

int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  for (int i = 0; i < n; i++) scanf("%d", as + i);
  int maxa = *max_element(as, as + n);

  int x0 = 0, x1 = maxa + 1;
  while (x0 + 1 < x1) {
    int x = (x0 + x1) / 2;
    if (check(n, x)) x0 = x;
    else x1 = x;
  }

  printf("%d\n", x0 / m);
  return 0;
}