If I were C, I would convince B that we should together try to kill A first because he is a better shooter and can kill one or both of us anytime. So when B starts firing at A, A will fire back at him. At the same instant, I will fire at B, kill him and let A realise that I saved his life. A will extend a hand of friendship towards me, and when he comes for a handshake, I will shoot him too. Khallas , James Bond for you :)