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


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

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

vector<int> a;

bool isPossible(int n, int k, int mid){
	
	int sum = 0;
	for(int i=0; i<n; i++) sum += a[i];
	
	int steps = 0;
	for(int i=n-1; i>=1; i--){
		
		if(steps > mid) return false;
		if(sum <= k) return true;
		
		if(a[i] > a[0]){
			int diff = a[i]-a[0];
			sum -= diff;
			steps++;
		}
	}

	int remSum = k - sum;
	
	int remSteps = remSum;
	
	return steps + remSteps <= mid;
	
}

int consistency(int n, int k){
	if(n==1){
		if(a[0] <= k) return 0;
		return a[0]-k;
	}
	
	sort(begin(a), end(a));
	
	int s = 0, e = INF;
	while(s<e){
		int mid = s + (e-s)/2;
		if(isPossible(n, k, mid)){
			e = mid;
		}
		else s = mid+1;
	}
	
	return e;
}

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;
}