#include <bits/stdc++.h>
using namespace std;
#define int              long long int
#define double           long double
#define print(a)         for(auto x : a) cout << x << " "; cout << endl


const int M = 1000000007;
const int N = 3e5+9;
const int INF = 2e9+1;
const int LINF = 2000000000000000001;

inline int power(int a, int b, int mod=M) {
    int x = 1;
    a %= mod;
    while (b) {
        if (b & 1) x = (x * a) % mod; 
        a = (a * a) % mod;
        b >>= 1;
    }
    return x;
}


//_ ***************************** START Below *******************************




vector<int> a;

bool isPossible(int n, int k, int total, int mid){

    if(total - mid <= k) return true;

    int revSum = 0;
    for(int i=n-1; i>=max(1LL, n-mid); i--){
        revSum += a[i];

        int sum = total - a[0] - revSum + (n-i+1)*(a[0] - (mid-(n-i)));
        if(sum <= k) return true;
    }

    return false;

}

int consistency(int n, int k){
    if(n==1){
        if(a[0] > k) return a[0]-k;
    }

    sort(begin(a), end(a));


    int total = 0;
    for(auto& it : a) total += it;
    if(k>=total) return 0;

    int s = 0;
    int e = INF;

    while(s<e){
        int mid = s + (e-s)/2;
        if(isPossible(n, k, total, mid)){
            e = mid;
        }
        else s = mid+1;
    }

    return e;
}















int practice(int n, int k){


    return 0;
}





void solve() {
    
    int n, k;
    cin>> n >> k;
    
    a.resize(n);
    for(int i=0; i<n; i++) cin >> a[i];
    
    cout << consistency(n, k) << endl;


}





int32_t main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    int t = 1;
    cin >> t;
    while (t--) {
        solve();
    }

    return 0;
}