#include<bits/stdc++.h>

using namespace std;

const int N = 1e5 + 5;
const long long INF = 2e14;

int n, k;
long long l = 0, r = INF, a[N];

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

int main(){
  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;
}