#include <bits/stdc++.h>

using namespace std;

const int N = 1e5 + 5;
const long long INF = 1e15;

int n, k;
long long l, r = INF, a[N];

bool Check(long long x) {
  long long cnt = 0, sum = 0;
  for (int i = 1; i <= n; i++) {
    if (a[i] + sum < x) {
      long long j = (x - a[i] - sum + i - 1) / i;
      cnt += j, sum += i * j;
    }
  }
  return cnt <= k;
}

int main() {
  ios::sync_with_stdio(0), cin.tie(0);
  cin >> n >> k;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  while (l < r) {
    long long mid = (l + r + 1) >> 1;
    Check(mid) ? l = mid : r = mid - 1;
  }
  cout << l;
  return 0;
}