C++ :

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

long long n,m,a[1000100],ma;

//check函数 
long long check(long long x){
	long long ans = 0;
	for(int i = 1;i <= n;i++){
		if(a[i] > x){
			ans = ans + (a[i] - x);
		}
	}
	return ans;
}

int main(){
	cin>>n>>m;
	for(int i = 1;i <= n;i++){
		cin>>a[i]; 
		ma = max(a[i],ma);//求最大 
	}
	
	long long l=1,r=ma,mid;
	while(l <= r){
		mid = (l + r) >>1;
		if(check(mid) < m) r = mid-1;
		else l = mid + 1;
	}
	cout<<l-1;
}