#ifdef LOCAL
#include <local.hpp>
#else
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2")
#include <bits/stdc++.h>
#define debug(...) (static_cast<void>(0))
#define postprocess() (static_cast<void>(0))
#endif

// #include "atcoder/dsu.hpp"
// #include "atcoder/modint.hpp"
// using mint = atcoder::modint998244353;
// using mint = atcoder::modint1000000007;

using namespace std;
using ll = long long;
using ld = long double;

void solve([[maybe_unused]] int test) {
    ll N, K;
    cin >> N >> K;

    ll A[N];
    for (int i = 0; i < N; i++) {
        cin >> A[i];
    }

    auto ok = [&](ll ans) {
        ll required = 0;
        ll sum = 0;

        for (ll i = 0; i < N; i++) {
            ll a = A[i] + sum;
            if (a >= ans) continue;

            ll num = (ans - a + i) / (i + 1);
            required += num;
            sum += num * (i + 1);
        }

        return required <= K;
    };

    ll imin = 0, imax = 1e16;
    while (imax - imin > 1) {
        ll imid = (imin + imax) / 2;
        if (ok(imid)) {
            imin = imid;
        } else {
            imax = imid;
        }
    }

    cout << imin << endl;
}

int main() {
    ios::sync_with_stdio(false), cin.tie(nullptr);

    int t = 1;
    // cin >> t;
    for (int _t = 1; _t <= t; _t++) solve(_t);

    postprocess();
}