Functions

Suppose \(f\) is a function satisfying \(f(x + y) = f(x) + f(y)\) for all \(x,y \in N\) and \(f(1) = {1 \over 5}\). If \(\sum\limits_{n = 1}^m {{{f(n)} \over {n(n + 1)(n + 2)}} = {1 \over {12}}}\), then \(m\) is equal to __________.