description: Consider a sequence of integers a_1, a_2, …, a_n. In one move, you can select any element of the sequence and delete it. After an element is deleted, all elements to the right are shifted to the left by 1 position, so there are no empty spaces in the sequence. So after you make a move, the sequence's length decreases by 1. The indices of the elements after the move are recalculated.
  
  E. g. let the sequence be a=[3, 2, 2, 1, 5]. Let's select the element a_3=2 in a move. Then after the move the sequence will be equal to a=[3, 2, 1, 5], so the 3-rd element of the new sequence will be a_3=1 and the 4-th element will be a_4=5.
  
  You are given a sequence a_1, a_2, …, a_n and a number k. You need to find the minimum number of moves you have to make so that in the resulting sequence there will be at least k elements that are equal to their indices, i. e. the resulting sequence b_1, b_2, …, b_m will contain at least k indices i such that b_i = i.
  
  Input
  
  The first line contains one integer t (1 ≤ t ≤ 100) — the number of test cases. Then t test cases follow.
  
  Each test case consists of two consecutive lines. The first line contains two integers n and k (1 ≤ k ≤ n ≤ 2000). The second line contains a sequence of integers a_1, a_2, …, a_n (1 ≤ a_i ≤ n). The numbers in the sequence are not necessarily different.
  
  It is guaranteed that the sum of n over all test cases doesn't exceed 2000.
  
  Output
  
  For each test case output in a single line:
  
    * -1 if there's no desired move sequence; 
    * otherwise, the integer x (0 ≤ x ≤ n) — the minimum number of the moves to be made so that the resulting sequence will contain at least k elements that are equal to their indices. 
  
  Example
  
  Input
  
  
  4
  7 6
  1 1 2 3 4 5 6
  5 2
  5 1 3 2 3
  5 2
  5 5 5 5 4
  8 4
  1 2 3 3 2 2 5 5
  
  
  Output
  
  
  1
  2
  -1
  2
  
  Note
  
  In the first test case the sequence doesn't satisfy the desired condition, but it can be provided by deleting the first element, hence the sequence will be [1, 2, 3, 4, 5, 6] and 6 elements will be equal to their indices.
  
  In the second test case there are two ways to get the desired result in 2 moves: the first one is to delete the 1-st and the 3-rd elements so that the sequence will be [1, 2, 3] and have 3 elements equal to their indices; the second way is to delete the 2-nd and the 3-rd elements to get the sequence [5, 2, 3] with 2 desired elements.
solution: import java.io.*;
  import java.util.*;
  //لخخخخخخخخخخخخخخخخخخخخخخخخخخخخسلسهعسس
  public final class Solution {
  
      static PrintWriter out = new PrintWriter(System.out);
      static FastReader in = new FastReader();
      static Pair[] moves = new Pair[]{new Pair(-1, 0), new Pair(1, 0), new Pair(0, -1), new Pair(0, 1)};
  
      // 1 2 3 5 6
      //
      public static void main(String[] args) {
          int tt = i();
          int mod = (int) 1e9 + 7;
  
          loop:
          while (tt-- > 0) {
              int n = i();
              int m = i();
              int[] a = input(n);
  
              int[][] dp = new int[n + 1][m + 1];
              for (int i = 1; i <= n; i++) {
                  Arrays.fill(dp[i], Integer.MAX_VALUE);
              }
  
              for (int i = 0; i < n; i++) {
                  if (i + 1 >= a[i] && a[i] <= n) {
                      int move = i + 1 - a[i];
                      dp[a[i]][1] = Math.min(dp[a[i]][1], move);
                      for (int k = Math.max(m - n + a[i], 2); k <= m; k++) {
                          for (int j = k - 1; j < a[i]; j++) {
                              if (dp[j][k - 1] <= move) {
                                  dp[a[i]][k] = Math.min(dp[a[i]][k], move);
                                  break;
                              }
                          }
                      }
                  }
              }
  
              int ans = Integer.MAX_VALUE;
              for (int i = 1; i <= n; i++) {
                  ans = Math.min(ans, dp[i][m]);
              }
              out.println(ans == Integer.MAX_VALUE ? -1 : ans);
          }
          out.flush();
      }
  
      static int[] pre(int[] a) {
          int[] pre = new int[a.length];
          pre[0] = a[0];
          for (int i = 1; i < a.length; i++) {
              pre[i] = pre[i - 1] + a[i];
          }
          return pre;
      }
  
      static void print(char A[]) {
          for (char c : A) {
              out.print(c);
          }
          out.println();
      }
  
      static void print(boolean A[]) {
          for (boolean c : A) {
              out.print(c + " ");
          }
          out.println();
      }
  
      static void print(int A[]) {
          for (int c : A) {
              out.print(c + " ");
          }
          out.println();
      }
  
      static void print(long A[]) {
          for (long i : A) {
              out.print(i + " ");
          }
          out.println();
      }
  
      static void print(List<Integer> A) {
          for (int a : A) {
              out.print(a + " ");
          }
      }
  
      static void printYes() {
          out.println("YES");
      }
  
      static void printNo() {
          out.println("NO");
      }
  
      static int i() {
          return in.nextInt();
      }
  
      static long l() {
          return in.nextLong();
      }
  
      static String s() {
          return in.nextLine();
      }
  
      static int[][] inputWithIdx(int N) {
          int A[][] = new int[N][2];
          for (int i = 0; i < N; i++) {
              A[i] = new int[]{i, in.nextInt()};
          }
          return A;
      }
  
      static int[] input(int N) {
          int A[] = new int[N];
          for (int i = 0; i < N; i++) {
              A[i] = in.nextInt();
          }
          return A;
      }
  
      static long[] inputLong(int N) {
          long A[] = new long[N];
          for (int i = 0; i < A.length; i++) {
              A[i] = in.nextLong();
          }
          return A;
      }
  
      static int GCD(int a, int b) {
          if (b == 0) {
              return a;
          } else {
              return GCD(b, a % b);
          }
      }
  
      static long GCD(long a, long b) {
          if (b == 0) {
              return a;
          } else {
              return GCD(b, a % b);
          }
      }
  
      static long LCM(int a, int b) {
          return (long) a / GCD(a, b) * b;
      }
  
      static long LCM(long a, long b) {
          return a / GCD(a, b) * b;
      }
  
      static void shuffleAndSort(int[] arr) {
          for (int i = 0; i < arr.length; i++) {
              int rand = (int) (Math.random() * arr.length);
              int temp = arr[rand];
              arr[rand] = arr[i];
              arr[i] = temp;
          }
          Arrays.sort(arr);
      }
  
      static void shuffleAndSort(int[][] arr, Comparator<? super int[]> comparator) {
          for (int i = 0; i < arr.length; i++) {
              int rand = (int) (Math.random() * arr.length);
              int[] temp = arr[rand];
              arr[rand] = arr[i];
              arr[i] = temp;
          }
          Arrays.sort(arr, comparator);
      }
  
      static void shuffleAndSort(long[] arr) {
          for (int i = 0; i < arr.length; i++) {
              int rand = (int) (Math.random() * arr.length);
              long temp = arr[rand];
              arr[rand] = arr[i];
              arr[i] = temp;
          }
          Arrays.sort(arr);
      }
  
      static boolean isPerfectSquare(double number) {
          double sqrt = Math.sqrt(number);
          return ((sqrt - Math.floor(sqrt)) == 0);
      }
  
      static void swap(int A[], int a, int b) {
          int t = A[a];
          A[a] = A[b];
          A[b] = t;
      }
  
      static long pow(long a, long b, int mod) {
          long pow = 1;
          long x = a;
          while (b != 0) {
              if ((b & 1) != 0) {
                  pow = (pow * x) % mod;
              }
              x = (x * x) % mod;
              b /= 2;
          }
          return pow;
      }
  
      static long pow(long a, long b) {
          long pow = 1;
          long x = a;
          while (b != 0) {
              if ((b & 1) != 0) {
                  pow *= x;
              }
              x = x * x;
              b /= 2;
          }
          return pow;
      }
  
      static long modInverse(long x, int mod) {
          return pow(x, mod - 2, mod);
      }
  
      static boolean isPrime(long N) {
          if (N <= 1) {
              return false;
          }
          if (N <= 3) {
              return true;
          }
          if (N % 2 == 0 || N % 3 == 0) {
              return false;
          }
          for (int i = 5; i * i <= N; i = i + 6) {
              if (N % i == 0 || N % (i + 2) == 0) {
                  return false;
              }
          }
          return true;
      }
  }
  
  class Pair {
  
      int i, j;
  
      Pair(int i, int j) {
          this.i = i;
          this.j = j;
      }
  }
  
  class FastReader {
  
      BufferedReader br;
      StringTokenizer st;
  
      public FastReader() {
          br = new BufferedReader(new InputStreamReader(System.in));
      }
  
      String next() {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      }
  
      int nextInt() {
          return Integer.parseInt(next());
      }
  
      long nextLong() {
          return Long.parseLong(next());
      }
  
      double nextDouble() {
          return Double.parseDouble(next());
      }
  
      String nextLine() {
          String str = "";
          try {
              str = br.readLine();
          } catch (IOException e) {
              e.printStackTrace();
          }
          return str;
      }
  }