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

int main() {
	cin.tie(nullptr);
	ios_base::sync_with_stdio(false);
	
	int N;
	ll K;
	cin >> N >> K;
	vector<ll> A(N);
	for (int i = 0; i < N; i++) cin >> A[i];
	
	ll ok = 0, ng = 1e16;
	while (ng - ok > 1) {
		ll mid = (ng - ok) / 2 + ok;
		
		ll t = 0;
		ll sum = 0;
		for (int i = 0; i < N; i++) {
			ll B = A[i] + sum;
			if (B >= mid) continue;
			
			ll d = (mid - B + i) / (i + 1);
			t += d;
			sum += d*(i + 1);
			if (t > K) break;
		}
		
		if (t > K) ng = mid;
		else ok = mid;
	}
	cout << ok << '\n';
}