program main
	implicit none
    integer W, a, b
	read(*, *) W, a, b
	if(b - (a+W) >= 0) then
		write(*, *) b - (a+W)
	else if(a - (b+W) >= 0) then
		write(*, *) a - (b+W)
	else
		write(*, *) 0
	end if
end program main