#include <bits/stdc++.h>

using namespace std;
using LL = long long;

const int MAXN = 1e5 + 3;

int n;
LL k, a[MAXN];

bool as(LL MIN){
  LL _k = k;
  for(LL i = 1, s = 0; i <= n; i++){
    if(a[i] + s < MIN){
      LL cnt = (MIN - (a[i] + s) + i - 1) / i;
      _k -= cnt;
      if(_k < 0) return 0;
      s += cnt * i;
    }
  }
  return 1;
}

int main(){
  ios::sync_with_stdio(0), cin.tie(0);
  cin >> n>> k;
  for(int i = 1; i <= n; i++){
    cin >> a[i];
  }
  LL l = 0, r = 1e17;
  while(l < r){
    LL mid = (l + r + 1) >> 1;
    if(as(mid)){
      l = mid;
    }else{
      r = mid - 1;
    }
  }
  cout << l;
  return 0;
}