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 Main {
      class JoinSet {
          int[] fa;
  
          JoinSet(int n) {
              fa = new int[n];
              for (int i = 0; i < n; i++) fa[i] = i;
          }
  
          int find(int x) {
              if (x != fa[x]) fa[x] = find(fa[x]);
              return fa[x];
          }
  
          void join(int x, int y) {
              x = find(x);
              y = find(y);
              fa[x] = y;
          }
      }
      static BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
      static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
      static int mod = (int) 1e9 + 7;
      static boolean[] isprime = new boolean[1];
      static {
          for (int i = 2; i < isprime.length; i++) isprime[i] = true;
          for (int i = 2; i < isprime.length; i++) {
              if (isprime[i]) {
                  for (int k = 2; i * k < isprime.length; k++) {
                      isprime[i * k] = false;
                  }
              }
          }
      }
      public static long gcd(long a, long b) {
          return b == 0 ? a : gcd(b, a % b);
      }
      public static long lcm(long a, long b) {
          return a * b / gcd(a, b);
      }
      public static int get() throws Exception {
          String ss = bf.readLine();
          if (ss.contains(" ")) ss = ss.substring(0, ss.indexOf(" "));
          return Integer.parseInt(ss);
      }
      public static int[] getInt() throws Exception {
          String s[] = bf.readLine().split(" ");
          int[] a = new int[s.length];
          for (int i = 0; i < a.length; i++) {
              a[i] = Integer.parseInt(s[i]);
          }
          return a;
      }
      public static long[] getLong() throws Exception {
          String s[] = bf.readLine().split(" ");
          long[] a = new long[s.length];
          for (int i = 0; i < a.length; i++) {
              a[i] = Long.parseLong(s[i]);
          }
          return a;
      }
      public static void print(int[] a) throws Exception {
          for (int i : a) {
              bw.write(i + " ");
          }
          println();
      }
      public static void print(long[] a) throws Exception {
          for (long i : a) {
              bw.write(i + " ");
          }
          println();
      }
      public static void print(String a) throws Exception {
          bw.write(a + "\n");
      }
      public static void print(int a) throws Exception {
          bw.write(a + "\n");
      }
      public static void print(long a) throws Exception {
          bw.write(a + "\n");
      }
      public static void println() throws Exception {
          bw.write("\n");
      }
      public static long pow(long a, long b) {
          long ans = 1;
          while (b > 0) {
              if ((b & 1) == 1) {
                  ans *= a;
              }
              a *= a;
              b >>= 1;
          }
          return ans;
      }
      public static int powmod(long a, long b, int mod) {
          long ans = 1;
          while (b > 0) {
              if ((b & 1) == 1) {
                  ans = ans * a % mod;
              }
              a = a * a % mod;
              b >>= 1;
          }
          return (int) ans;
      }
      public static void sort(int[] a) {
          int n = a.length;
          Integer[] b = new Integer[n];
          for (int i = 0; i < n; i++) b[i] = a[i];
          Arrays.sort(b);
          for (int i = 0; i < n; i++) a[i] = b[i];
      }
      public static void sort(long[] a) {
          int n = a.length;
          Long[] b = new Long[n];
          for (int i = 0; i < n; i++) b[i] = a[i];
          Arrays.sort(b);
          for (int i = 0; i < n; i++) a[i] = b[i];
      }
  
      public static void main(String[] args) throws Exception {
          int t = get();
          while (t-- > 0) {
              long m[] = getLong();
              int n = (int)m[0];
              long k = m[1];
              long[] a = getLong();
              sort(a);
              long sum = Arrays.stream(a).sum();
              long ans = Long.MAX_VALUE;
              if(sum > k){
                  sum -= a[0];
                  for(int i = 0;i < n;i++){
                      long d = sum + a[0]*(i+1); //逐步将每一个数都换成a[0],ans取替换0、1、2...个的最小值
                      long need = 0;
                      if (d > k) {
                          need = (d-k+i) / (i + 1);
                      }
                      ans = Math.min(ans, i + need);
                      sum -= a[n-1-i];
                  }
              }else{
                  ans = 0;
              }
              print(ans);
          }
          bw.flush();
      }
  }