// #include <bits/stdc++.h>
#include <string.h>

#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <ciso646>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

#define For(i, a, b) for (int i = (int)(a); (i) < (int)(b); ++(i))
#define rFor(i, a, b) for (int i = (int)(a)-1; (i) >= (int)(b); --(i))
#define rep(i, n) For(i, 0, n)
#define rrep(i, n) rFor(i, n, 0)
#define fi first
#define se second


#include <algorithm>
#include <cassert>
#include <vector>

namespace rklib {

template <class T>
bool chmax(T &a, const T &b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

template <class T>
bool chmin(T &a, const T &b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

template <class T>
bool chmin_non_negative(T &a, const T &b) {
    if (a < 0 || a > b) {
        a = b;
        return true;
    }
    return false;
}

template <class T>
T div_floor(T a, T b) {
    if (b < 0) a *= -1, b *= -1;
    return a >= 0 ? a / b : (a + 1) / b - 1;
}

template <class T>
T div_ceil(T a, T b) {
    if (b < 0) a *= -1, b *= -1;
    return a > 0 ? (a - 1) / b + 1 : a / b;
}

}  // namespace rklib


using namespace std;
using namespace rklib;

using lint = long long;
using pii = pair<int, int>;
using pll = pair<lint, lint>;

int main() {
    int n;
    lint K;
    scanf("%d%lld", &n, &K);
    lint a[n];
    rep(i, n) scanf("%lld", &a[i]);

    lint low = 0, high = 10'000'000'000'000'000;
    while (high - low > 1) {
        lint mid = (high + low) / 2;

        lint cnt = 0;
        lint sum = 0;
        rep(i, n) {
            if (a[i] + sum < mid) {
                lint need = div_ceil(mid - a[i] - sum, lint(i + 1));
                cnt += need;
                sum += need * (i + 1);
                if (cnt > K) {
                    break;
                }
            }
        }
        (cnt <= K ? low : high) = mid;
    }
    printf("%lld\n", low);
}