Let P(x)=x3+ax2+b and Q(x)=x3+bx+a, where a, b are non-zero real numbers. Suppose that the roots of the equation P(x) = 0 are the reciprocals of the roots of the equation Q(x) = 0. Prove that a and b are integers. Find the greatest common divisor of P(2013! + 1) and Q(2013! + 1). (RMO 2013, Mumbai Region)