For certain real values of $$a, b, c,$$ and $$d_{},$$ the equation $$x^4+ax^3+bx^2+cx+d=0$$ has four non-real roots. The product of two of these roots is $$13+i$$ and the sum of the other two roots is $$3+4i,$$ where $$i=\sqrt{-1}.$$ Find $$b.$$

(第十三届AIME1995 第5题)