#!/usr/bin/env python

def stridesTaken(flights, stairsPerStride):
	number_of_strides = 0
	if flights[0] % stairsPerStride:
		number_of_strides = flights[0] / stairsPerStride + 1
	else:
		number_of_strides = flights[0] / stairsPerStride

	for flight in flights[1:]:
		print "taken %d strides so far" % number_of_strides
		if flight % stairsPerStride:
			number_of_strides = number_of_strides + (flight / stairsPerStride) + 1
		else:
			number_of_strides = number_of_strides + (flight / stairsPerStride)
		number_of_strides = number_of_strides + 2

	print "took %d steps \n--------------------" % number_of_strides
	return number_of_strides



if __name__ == "__main__":
	print "--------------------"
	assert stridesTaken([15], 2) == 8, "WRONG"
	assert stridesTaken([15,15], 2) == 18, "WRONG"
	assert stridesTaken([5,11,9,13,8,30,14], 3) == 44, "WRONG"