#!/bin/python

import math
import os
import random
import re
import sys

# Complete the minuteToWinIt function below.
def minuteToWinIt(a, k, n):
  valores = dict()
  for i in range(0, n):
    val = a[i] - k*i
    if(val in valores):
      valores[val] += 1
    else:
      valores[val] = 1

  max = 0
  for values in valores:
    if max < valores[values]:
      max = valores[values]

  return (n - max)

if __name__ == '__main__':
  fptr = open(os.environ['OUTPUT_PATH'], 'w')

  nk = raw_input().split()

  n = int(nk[0])

  k = int(nk[1])

  a = map(int, raw_input().rstrip().split())

  result = minuteToWinIt(a, k, n)

  fptr.write(str(result) + '\n')

  fptr.close()