The Green Cab Company has a taxi waiting at each of four cabstands in Evanston, Illinois. Four customers have called and requested service. The distances, in miles, from the waiting taxis to the customers are given in the following table. The optimal assignment of taxis to customers that minimizes the distance is: Customer A $->$ Customer B $->$ Customer C $->$ Customer D $->$ The cumulative distance of the optimal assignment of taxis to customers $=$ miles $($enter your response as a whole number$).$