So, you see we must we must sort of emphasis, that for v dash and r dash to reduce with time and eventually becomes 0, approach 0, sigma 1 sigma 2 must be real negative, this is very important. That means, my solution this see I have got this, what is my solution for this equation, see what is sigma 1 and 2 equal to minus, you see B by A plus minus by 2, this is everybody knows now, see the know actually I know no this is.