可以理解为把坑填平

填坑消耗的万能卡<=目标高度（4）时可以由经过平移变化，使每一层至多有一张万能卡

样例

4 5
2 3 4 5

   样例     填坑后    平移变化
0 0 0 1   0 0 0 1    0 0 0 1
0 0 1 1   x x 1 1    x 1 1 1
0 1 1 1-->x 1 1 1--->x 1 1 1
1 1 1 1   1 1 1 1    x 1 1 1
1 1 1 1   1 1 1 1    1 1 1 1

#include <bits/stdc++.h>
using namespace std;
#define int long long 
int n, m;
bool check(int x,vector<int>&a){
	int diff = 0;//diff为消耗的万能卡，图中的x
	for (int i = 1; i <= n; i++) {
		if (a[i] < x)diff += x - a[i];
		if (diff > m || diff > x){
			return false;
		}
	}
	return true;
}


signed main() {
	cin >> n >> m;
	vector<int>num(n+1);
	for (int i = 1; i <= n; i++)cin >> num[i];
	sort(num.begin() + 1, num.end());
	int l = num[1], r = num[n];

	//对目标高度二分
	while (l < r) {
		int mid = l + (r - l + 1) / 2;
		if (check(mid, num))l = mid;
		else r = mid - 1;
	}
	cout << l;
	return 0;
}