program sample
    implicit none
  
    integer(8) :: i,j,m,n,a(10000000)
    
    integer(8),allocatable :: x(:),y(:)
  
    read(*,*) n

    do i=1,10000000
        a(i)=0
    end do
    do i=1,n
        do j=1,n/i
             a(i*j)=a(i*j)+1
         end do
    end do
    m=0
    do i=1,n
        m=m+a(i)*i

    end do
    write(*,*) m
  
    stop
end program sample
  

