People are waiting for an elevator in a hotel that has floors numbered 0 to M. The elevator has a limit of X people and a weight limit of Y. There are N people standing in a queue at the ground floor. You are given two arrays: A[N], where each element is the weight of a person, and B[N], where each element is the floor each person wants to go to. The elevator goes up, stopping at each requested floor, then returns to the ground floor. Write a solution to determine how many times the elevator will stop.