module mdl

contains

    recursive subroutine qsort(a,s,t)
        integer*8::a(:),i,j,s,t,m
        if(t-s<=1)return
        i=s
        j=t-1
        m=a((s+t)/2)
        do
            do while(a(i)<m)
                i=i+1
            end do
            do while(a(j)>m)
                j=j-1
            end do
            if(i>=j)exit
            a(i)=xor(a(i),a(j))
            a(j)=xor(a(i),a(j))
            a(i)=xor(a(i),a(j))
            i=i+1
            j=j-1
        end do
        call qsort(a,s,i)
        call qsort(a,j+1,t)
    end subroutine

    function calc(c,trg)
        integer*8::calc,c(:),trg
        calc=0
        do i=1,size(c)
            calc=calc+abs(c(i)-trg)
        end do
    end function
end module


program main
    use mdl
    implicit none
    integer*8::b,n,tot=0,i,j,k,s,t,ans
    integer*8,allocatable::c(:)
    read*,b
    read*,n
    allocate(c(n))
    do i=1,n
        read*,c(i)
    end do

    call qsort(c,int(1,8),int(size(c),8))

    print*,calc(c,c((n+1)/2))
end program