#include <bits/stdc++.h>
using namespace std;

int main() {
    ios::sync_with_stdio(0); cin.tie(0);
    long long N, K; cin >> N >> K;
    vector<long long> A(N); for (long long &i : A) cin >> i;
    
    auto check = [&](long long x) -> bool {
        long long offset = 0, operations = 0;
        for (long long i = 0; i < N && operations <= K; ++i) {
            if (A[i] + offset < x) {
                operations += (x - A[i] - offset + i) / (i + 1);
                offset += (x - A[i] - offset + i) / (i + 1) * (i + 1);
            }
        }
        return operations <= K;
    };
    
    
    long long L = 1, R = 1e15, ans = 0;
    while (R >= L) {
        long long M = L + R >> 1;
        if (check(M) == true) {
            ans = M;
            L = M + 1;
        } else {
            R = M - 1;
        }
    }
    
    cout << ans << endl;
}