output_description: Print the smallest possible value of X-Y.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N K Q
      A_1 A_2 ... A_N
attempt: n, k, q = (int(i) for i in input().split())
  a = [int(i) for i in input().split()]
  ans = 10**9
  for i in a:
      p, s, f = [], 0, 1
      for j in range(n):
          if a[j] >= i and f:
              s, f = j, 0
          elif a[j] < i and f - 1:
              if j - s >= k:
                  for j2 in sorted(a[s:j])[: j - s - k + 1]:
                      p.append(j2)
              f = 1
      if f - 1 and n - s >= k:
          for j2 in sorted(a[s:n])[: n - s - k + 1]:
              p.append(j2)
      if len(p) >= q:
          ans = min(ans, sorted(p)[q - 1] - i)
  print(ans)
  
problem_description: Statement
  
  You are given an integer sequence A of length N and an integer K. You will
  perform the following operation on this sequence Q times:
  
    * Choose a contiguous subsequence of length K, then remove the smallest element among the K elements contained in the chosen subsequence (if there are multiple such elements, choose one of them as you like).
  
  Let X and Y be the values of the largest and smallest element removed in the Q
  operations. You would like X-Y to be as small as possible. Find the smallest
  possible value of X-Y when the Q operations are performed optimally.
samples: [{"input": "5 3 2\n    4 3 1 5 2", "output": "1\n    \n\nIn the first operation, whichever contiguous subsequence of length 3 we\nchoose, the minimum element in it is 1. Thus, the first operation removes\nA_3=1 and now we have A=(4,3,5,2). In the second operation, it is optimal to\nchoose (A_2,A_3,A_4)=(3,5,2) as the contiguous subsequence of length 3 and\nremove A_4=2. In this case, the largest element removed is 2, and the smallest\nis 1, so their difference is 2-1=1.\n\n* * *"}, {"input": "10 1 6\n    1 1 2 3 5 8 13 21 34 55", "output": "7\n    \n\n* * *"}, {"input": "11 7 5\n    24979445 861648772 623690081 433933447 476190629 262703497 211047202 971407775 628894325 731963982 822804784", "output": "451211184"}]