description: You are given an integer array a_1, a_2, ..., a_n and integer k.
  
  In one step you can 
  
    * either choose some index i and decrease a_i by one (make a_i = a_i - 1); 
    * or choose two indices i and j and set a_i equal to a_j (make a_i = a_j). 
  
  
  
  What is the minimum number of steps you need to make the sum of array ∑_{i=1}^{n}{a_i} ≤ k? (You are allowed to make values of array negative).
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 10^4) — the number of test cases.
  
  The first line of each test case contains two integers n and k (1 ≤ n ≤ 2 ⋅ 10^5; 1 ≤ k ≤ 10^{15}) — the size of array a and upper bound on its sum.
  
  The second line of each test case contains n integers a_1, a_2, ..., a_n (1 ≤ a_i ≤ 10^9) — the array itself.
  
  It's guaranteed that the sum of n over all test cases doesn't exceed 2 ⋅ 10^5.
  
  Output
  
  For each test case, print one integer — the minimum number of steps to make ∑_{i=1}^{n}{a_i} ≤ k.
  
  Example
  
  Input
  
  
  4
  1 10
  20
  2 69
  6 9
  7 8
  1 2 1 3 1 2 1
  10 1
  1 2 3 1 2 6 1 6 8 10
  
  
  Output
  
  
  10
  0
  2
  7
  
  Note
  
  In the first test case, you should decrease a_1 10 times to get the sum lower or equal to k = 10.
  
  In the second test case, the sum of array a is already less or equal to 69, so you don't need to change it.
  
  In the third test case, you can, for example: 
  
    1. set a_4 = a_3 = 1; 
    2. decrease a_4 by one, and get a_4 = 0. 
  
  As a result, you'll get array [1, 2, 1, 0, 1, 2, 1] with sum less or equal to 8 in 1 + 1 = 2 steps.
  
  In the fourth test case, you can, for example: 
  
    1. choose a_7 and decrease in by one 3 times; you'll get a_7 = -2; 
    2. choose 4 elements a_6, a_8, a_9 and a_{10} and them equal to a_7 = -2. 
  
  As a result, you'll get array [1, 2, 3, 1, 2, -2, -2, -2, -2, -2] with sum less or equal to 1 in 3 + 4 = 7 steps.
solution: import java.io.*;
  import java.util.*;
  
  public class codeforces{
      public static void main(String[] args) throws Exception {
          int T = in.nextInt();
          while(T --> 0){
              int N = in.nextInt();
              Long K = in.nextLong(); //upperbound
              Long[]a = new Long[N];
  
              long min = Integer.MAX_VALUE;
              long total = 0;
              for (int i = 0; i < N; i++){
                  a[i] = in.nextLong();
                  min = Math.min(min, a[i]);
                  total += a[i];
              }
              Arrays.sort(a);
              if(total <= K) {
                  out.println(0);
                  out.flush();
                  continue;
              }
  
              long[]prefixSum = new long[N+1];
              for (int i = 0; i < N; i++)
                  prefixSum[i + 1] = prefixSum[i] + a[i];
  
              long best = Integer.MAX_VALUE;
              //System.out.println(Arrays.toString(prefixSum));
              for (int sets = 0; sets <= N - 1; sets++) {
                  long sum = prefixSum[N - sets] + a[0] * sets;
                  //what the sum of the array would be after you changed the last N elements to the smallest element in the array
                  int reduce = sets + 1; //how much you are reducing the smallest number by?
                  long need = Math.max((sum - K + reduce - 1) / reduce, 0);
                  best = Math.min(best, need + sets);
              }
  
  
              out.println(best);
              out.flush();
          }
          out.close();
      }
      static final Kattio in = new Kattio();
      static long Int(String s){ return Long.parseLong(s);}
      static class Kattio extends PrintWriter {
          private BufferedReader r;
          private StringTokenizer st;
  
          // standard input
          public Kattio() {
              this(System.in, System.out);
          }
  
          public Kattio(InputStream i, OutputStream o) {
              super(o);
              r = new BufferedReader(new InputStreamReader(i));
          }
  
          // USACO-style file input
          public Kattio(String problemName) throws IOException {
              super(new FileWriter(problemName + ".out"));
              r = new BufferedReader(new FileReader(problemName + ".in"));
          }
  
          // returns null if no more input
          public String next() {
              try {
                  while (st == null || !st.hasMoreTokens())
                      st = new StringTokenizer(r.readLine());
                  return st.nextToken();
              } catch (Exception e) {
              }
              return null;
          }
  
          public int nextInt() {
              return Integer.parseInt(next());
          }
  
          public double nextDouble() {
              return Double.parseDouble(next());
          }
  
          public long nextLong() {
              return Long.parseLong(next());
          }
  
          public String readLine() throws Exception {
              return r.readLine();
          }
  
          public Long[] readArrayLong(int n) {
              Long[] arr = new Long[n];
              for (int i = 0; i < n; i++)
                  arr[i] = nextLong();
              return arr;
          }
  
          public Integer[] readArrayI(int n) {
              Integer[] arr = new Integer[n];
              for (int i = 0; i < n; i++)
                  arr[i] = nextInt();
              return arr;
          }
  
          public int[] readArray(int n) {
              int[] arr = new int[n];
              for (int i = 0; i < n; i++)
                  arr[i] = nextInt();
              return arr;
          }
  
          public int[]prefixSum(int N, int[]a){
              int[]nw = new int[N + 1];
              nw[0] = 0;
              for (int i = 0; i < N; i ++) {
                  nw[i + 1] = nw[i] + a[i];
              }
  
              return nw;
          }
  
          public int[][] prefixSum(int N, int[][]grid){
              int[][]pfx = new int[grid.length][grid.length];
              for (int i = 1; i < N + 1; i++) {
                  for (int j = 1; j < N + 1; j++) {
                      pfx[i][j] = grid[i][j]
                              + pfx[i-1][j]
                              + pfx[i][j-1]
                              - pfx[i-1][j-1];
                  }
              }
  
              return pfx;
          }
  
          public int prefixSum2D(int x1, int y1, int x2, int y2, int[][]pfx) {
              return pfx[x2][y2] - pfx[x1-1][y2] - pfx[x2][y1-1] + pfx[x1-1][y1-1];
          }
      }
      static final PrintWriter out = new PrintWriter(System.out);
      static class Pair implements Comparable<Pair> {
          int x, y;
  
          Pair (int x, int y) {
              this.x = x;
              this.y = y;
          }
  
          @Override
          public int compareTo (Pair other) {
              if(this.x == other.x) return Integer.compare(this.y, other.y);
              return Integer.compare(this.x, other.x);
          }
          public String toString() { return x + " " + y;}
      }
  }