#include<bits/stdc++.h>
#define REP(i,n) for(int i=0,i##_len=int(n);i<i##_len;++i)
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
#define All(x) (x).begin(),(x).end()
#define rAll(x) (x).rbegin(),(x).rend()
using namespace std;
using ll = long long;

int main(){
    int n,k;cin>>n>>k;
    vector<ll> a(n);
    REP(i,n) cin>>a[i];
    ll l = *std::min_element(All(a)), r=1e18;
    while(l+1<r){
        ll mid = (l+r)>>1;
        ll sum = 0;
        ll fc = 0;
        REP(i, n){
            ll now = a[i] + sum;
            if(mid - now > 0) {
                ll cnt = (mid-now + i) / (i+1);
                sum += cnt * (i+1);
                fc += cnt;
            }
        }
        if(fc <= k) l = mid;
        else r = mid;
    }
    cout << l << endl;
}