let n, a, b = Scanf.scanf " %d %d %d" @@ fun a b c -> a, b, c
let ans, xs = ref 0, Array.init n @@ fun _ -> Scanf.scanf " %d" (+) 0
let _ = Array.iteri (fun i x -> if i > 0 then ans := !ans + min b (a * (x - xs.(i - 1)))) xs; Printf.printf "%d\n" !ans