I was trying to solve this number theory problem from 2012-2013 ACM-ICPC, NEERC, Western Subregional Contest. The problem name is L : sum. In this problem we given a number N and we want K(any K that works) natural numbers such that their sum is N and sum of their reciprocal is 1. How to solve this ? I tried various approaches but wasn't able to generalize for all N.