#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <cmath>
#include <iomanip>
#include <stack>
#include <queue>
#include <numeric>
#include <map>
#include <unordered_map>
#include <set>
#include <fstream>
#include <chrono>
#include <random>
#include <bitset>
//#include <atcoder/all>
#define rep(i,n) for(int i=0;i<(n);i++)
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) ((int)(x).size())
#define pb push_back
using ll = long long;
using namespace std;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
ll gcd(ll a, ll b) {return b?gcd(b,a%b):a;}
ll lcm(ll a, ll b) {return a/gcd(a,b)*b;}

using ull = unsigned long long;

int main(){
  int N; ull K; cin >> N >> K;
  vector<ull> A(N);
  rep(i,N) cin >> A[i];
  ull ok = *min_element(all(A)), ng = 1ull<<50;
  while(ng-ok>1){
    ull mid = (ok+ng)/2;
    ull ad = 0;
    ull op = 0;
    rep(i,N){
      if(A[i]+ad<mid){
        ull x = mid-(A[i]+ad);
        ull adop = (x+i)/(i+1);
        op += adop;
        ad += adop * (ull)(i+1);
        if(op>K) break;
      }
    }
    if(op<=K) ok = mid;
    else ng = mid;
  }
  cout << ok << endl;
  return 0;
}