EE-MO 2003 Problem 1

Let $A_1, A_2, ..., A_m$ and $B_2 , B_3,..., B_n$ be the points on a circle such that $A_1A_2... A_n$ is a regular $m$ -gon and $A_1B_2...B_n$ is a regular $n$ -gon whereby $n > m$ and the point $B_2$ lies between $A_1$ and $A_2$ . Find $\angle B_2A_1A_2$ .