def get_N_teachers(school_type, N_classes):
	"""Return the number of teachers / class for different school types."""
	teachers = {
		'primary':N_classes + int(N_classes / 2),
		'primary_dc':N_classes * 2,
		'lower_secondary':int(N_classes * 2.5),
		'lower_secondary_dc':N_classes * 3,
		'upper_secondary':int(N_classes * 2.85),
		'secondary':int(N_classes * 2.5),
		'secondary_dc':int(N_classes * 2.5)
	}
	return teachers[school_type]