import sys

while 1:
  try:
    input()
  except:
    break
  nums = [int(i) for i in input().split(' ')]
  if len(nums) == 1:
    print(1)
  else:
    i = len(nums)
    a, b = nums[i - 2], nums[i - 1]
    d = a - b
    while d == a - b and i > 1:
  #    print(a, b, d, i, a - b)
      i -= 1
      a, b = nums[i - 2], nums[i - 1]
  #    print(a, b, d, i, a - b)
    print(i)