Problem Statement  
*** You may only submit a given problem once  no resubmissions will be accepted. *** Salesmen and saleswomen often work for a commission. In other words, they get to keep a certain percentage of the sales they make. You have a saleswoman working for you who gets a whopping 20% commission, which cuts deep into your profit margins. You are considering replacing her with a cheaper salesman who will keep commission% of his sales. Out of each sale, cost% of the sale goes towards the cost of your products and other overhead. Your current saleswoman sells $sales of products a year. Your task is to determine how much the potential salesman would have to sell in a year to make you the same profit.  
Definition  
 
Notes  
  Your result must have relative or absolute error of less than 1e9.  
  The commission is based on the gross sale, not the part of the sale that is above and beyond the cost. Therefore, if sales were $1000, your current saleswoman's commission would be $200.  
  Note that neither sales nor the return value need to be in whole cents.  
Constraints  
  sales will be between 1 and 1e10, inclusive.  
  cost will be between 0.5 and 79.5, inclusive.  
  commission will be between 0.5 and 19.5, inclusive.  
Examples  
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