#include <bits/stdc++.h>
#include <atcoder/all>
#include <vector>
#include <set>
#include <queue>
#include <utility>
#include <map>
#include <regex>
#include <math.h>
#include <random>
#include <algorithm>
#define pb push_back
#define all(x) begin(x), end(x)
#define gall(x) begin(x), end(x), greater<>()
#define ll long long
#define rep(i,x) for(int i=0;i<x;i++)
#define P pair<int, int>
#define lP pair<ll, ll>
using namespace std;
using namespace atcoder;
using mint=modint998244353;

const int INF=1e9;

int main()
{ 
   ll n,K; cin>>n>>K;
   vector<ll> a(n+1);
   for(int i=1;i<=n;i++) cin>>a[i];
   ll ok=-1,ng=a[1]+K+5;
   while(ng-ok>1){
    ll k=K;
    ll mid=(ok+ng)/2;
    ll s=0;
   for(ll i=1;i<=n;i++){
    ll ai=a[i]+s;
    if(ai<mid){
        ll cnt=(mid-ai+i-1)/i;
        k-=cnt;
        s+=cnt*i;
    }
   }
   if(k>=0) ok=mid;
   else ng=mid;
   }
   cout<<ok<<endl;

return  0;
}