implicit none
integer(8) i,m,n,a,B
integer(8),allocatable :: x(:)
read(*,*) n,a
allocate (x(n))
read(*,*) (x(m),m=1,n)
B=0
do i=1,n
   B=B+x(i)
end do
if (B==(a*n)) then
    write(*,*) "YES"
else
    write(*,*) "NO"
end if
end