MIT: Introduction to Computer Science and Programming in Python : problem set 2 problem c

best saving rate

original_salary = float(input("Enter annual salary "))
house_cost_in_millions = int(input("Enter House cost in millions "))
house_cost = house_cost_in_millions * 1000000
down_payment = 0.25*house_cost
semi_annual_raise = 0.07
annual_investment_return = 0.04

delta = 101
low = 0
high = 1000
total_years = int(input("Enter total number of years "))
total_max_months = total_years * 12
savings = 0
steps =0
best_savings_rate = (low+high)/2.0

while(delta>100):
	annual_salary = original_salary
	monthly_salary = annual_salary/12	
	months=0
	savings=0

	while(months<total_max_months):
		if (months!=0) and (months%6==0):
			annual_salary = annual_salary + (annual_salary*semi_annual_raise)
			monthly_salary = annual_salary/12

		savings = savings + (savings*(annual_investment_return/12))
		savings = savings + monthly_salary * (best_savings_rate/100)	
		months+=1	
		
	 
	delta = abs(savings-down_payment)
	 
	if (savings>down_payment):
		high = best_savings_rate
	else:
		low = best_savings_rate

	best_savings_rate = (low+high)/2
	steps+=1


if (best_savings_rate<=100):
	print("best savings rate {:.4f}".format(best_savings_rate/100))
	print("steps {}".format(steps))
	save_annually = original_salary*(best_savings_rate/100)
	print("You need to save ${:.4f} per year".format(save_annually))
else:
	  print("It is not possible to pay the down payment in three years")