program walk_and_teleport
  implicit none
  integer :: n
  integer(8) :: a, b, x(100000) = 0_8, y(100000) = 0_8, z(100000) = 0_8
  read(*,*) n, a, b
  read(*,*) x(1:n)
  y(1:n-1) = a*(x(2:n)-x(1:n-1))
  z(1:n-1) = b
  write(*,'(i0)') sum(merge(y,z,y<z))
  stop
end program walk_and_teleport