How many cigarettes can I bring back from Sri Lanka, Singapore and Malaysia as well as between the countries?

I am going on a rugby tour between these countries and my friend has asked for me to get him some cigarettes. We will be visiting either Singapore or Malaysia last (I cannot find the details at the moment) so I am wondering how many cigarettes I can bring home with me. Also I am wondering how many I can bring between the countries in case I find cheap ones in Sri Lanka and buy them there.