#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for (long long i=0;i<(long long)(n);i++)
#define all(v) v.begin(),v.end()
using ll=long long;
using pll=pair<ll,ll>;
using tll=tuple<ll,ll,ll>;
const ll INF=(1ll<<60);
template<class T> void chmin(T &a,T b){
    if(a>b){
        a=b;
    }
}
template<class T> void chmax(T &a,T b){
    if(a<b){
        a=b;
    }
}
int main(){
    ll n,k;
    cin >> n >> k;
    vector<ll> a(n);
    rep(i,n) cin >> a[i];
    ll ng=INF,ok=0;
    while(1<abs(ok-ng)){
        ll mid=(ok+ng)/2;
        vector<ll> b(n);
        rep(i,n) b[i]=max(0ll,mid-a[i]);
        ll cnt=0,now=0;
        rep(i,n){
            ll x=max(0ll,(b[i]-now+i+1-1)/(i+1));
            cnt+=x;
            now+=x*(i+1);
        }
        if(cnt<=k) ok=mid;
        else ng=mid;
    }
    cout << ok << endl;
}