#include <bits/stdc++.h>

using i64 = long long;

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    int n, k;
    std::cin >> n >> k;
    
    std::vector<i64> a(n);
    for (int i = 0; i < n; i++) {
        std::cin >> a[i];
    }
    
    i64 lo = 0, hi = 2E14;
    
    while (lo < hi) {
        i64 x = (lo + hi + 1) / 2;
        
        i64 need = 0;
        i64 add = 0;
        for (int i = 0; i < n; i++) {
            i64 cur = a[i] + add;
            if (cur < x) {
                i64 t = (x - cur + i) / (i + 1);
                need += t;
                add += t * (i + 1);
            }
        }
        
        if (need <= k) {
            lo = x;
        } else {
            hi = x - 1;
        }
    }
    
    std::cout << lo << "\n";
    
    return 0;
}