#Sentinel Loop Control
	print("Enter temperature observations, -300 to stop")
	count = 0
	sum = 0.0
	temp = float(input("First temperature: "))
	while temp > -300.0:
	sum += temp
	count += 1
	temp = float(input("Next temperature: "))
	if count > 0:
	print("Average temperature =", sum / count)
	else:
	print("No valid data entered")