#include <bits/stdc++.h>
#define int long long
typedef long long ll;
using namespace std;
 
void solve() {
    int n,x;
    cin >> n >>x;
   vector<int> v(n);
   for(int i=0;i<n;i++){
   		cin>>v[i];
   }
   int low=1,high=1e10;
   int ans=INT_MIN;
   while(low<=high){
   	int h=(low+high)/2;
   	int sum=0;
   	for(int i=0;i<n;i++){
   		sum+=max(0ll,h-v[i]);
   	}
   	if(sum>x){
   		high=h-1;
   	}
   	else{
   		ans=max(ans,h);
   		low=h+1;
   	}
   }
   cout<<ans<<endl;
 
}
 
signed main() {
    int t;
    cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}
 

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NQo3IDkKMyAxIDIgNCA2IDIgNQozIDEwCjEgMSAxCjQgMQoxIDQgMyA0CjYgMTk4NAoyIDYgNSA5IDEgOAoxIDEwMDAwMDAwMDAKMQo=

5
7 9
3 1 2 4 6 2 5
3 10
1 1 1
4 1
1 4 3 4
6 1984
2 6 5 9 1 8
1 1000000000
1