def basal_metabolic_rate(gender, weight, height, age):
	"""Calculate and return a person's basal metabolic rate (bmr).
	Parameters:
	weight must be in kilograms.
	height must be in centimeters.
	age must be in years.
	Return: a person's basal metabolic rate in kcal per day.
	"""
	if gender == "M":
		bmr = 88.362 + 13.397 * weight + 4.799 * height - 5.677 * age
	elif gender == "F":
		bmr = 447.593 + 9.247 * weight + 3.098 * height - 4.330 * age
	else:
		bmr = -1
	return round(bmr, 0)