program sample
    implicit none
    character(100)::s,t
    integer(8) :: i,j,k,m,n
    integer(8)::a,b,c,d
    integer(8),allocatable::x(:),y(:)
  
    read(*,*) a
    if(mod(a,2)==0)then
        write(*,*)(a/2)**2
    else
        write(*,*)a/2*(a/2+1)
    endif
    stop
end program sample
  

