Let the probability of getting head for a biased coin be $$\frac{1}{4}$$. It is tossed repeatedly until a head appears. Let $$N$$ be the number of tosses required. If the probability that the equation $$64x^2 + 5Nx + 1 = 0$$ has no real root is $$\frac{p}{q}$$, where $$p$$ and $$q$$ are co-prime, then $$q - p$$ is equal to _______