import sys

is_first_input = False



for line in sys.stdin:
	if not is_first_input:	
		start_input = int(line.rstrip())
		#print ("start_input = ", start_input)
		is_first_input = True
	else:
			#print ("start_input = ", start_input)
		if start_input == 1 or start_input == 2:
			print(1)
			is_first_input = False
			continue
		
		numbers = list(map(int, line.rstrip().split(' ')))
		
		#print(numbers)
		
		#if len(numbers) == 1:
			
		
		#if len(numbers) == 2:
		#	print(1)
		#	isFirstInput = False
		#	continue

		numbers.reverse()
		#print(numbers)
		answer_index = len(numbers) - 1

		delta = numbers[0] - numbers[1]
		#print("delta = ", delta, ", numbers[0] =", numbers[0], ", numbers[1] = ", numbers[1])
		for i in range(len(numbers)):
			if i < 2:
				continue
			else:
				if numbers[i - 1] - numbers[i] == delta:
					answer_index -= 1
				else:
					#print("numbers[i] - numbers[i - 1] =", numbers[i] - numbers[i - 1])
					#print(answer_index)
					break
					
		print(answer_index)
		is_first_input = False