The chord of the contact of tangents drawn from point on the circle x^2 + y^2 = a^2x2+y2=a2 to the circle x^2 + y^2 = b^2x2+y2=b2 touches the circle x^2 + y^2 = c^2x2+y2=c2 such that b^p = a^m c^nbp=amcn where m, n, p \in Nm,n,p∈N, and m, n, p are prime to each other, then the value of 2m + n + 2p - 3 is: