Bags and Balls

You are given $N$ empty bags. Provided with $K$ numbers of balls you have to put those balls in the bags. Also, you have to put the balls in a sequence i.e. given a number $R$, the balls you put in the bags should be in increasing multiples of $R$. For example, if R=5 then the balls in the bags are in sequence 5,10,15,20... Now your task is to find how many bags remain empty. - Note: The balls in