given , f(x)=2*(f(x-1)+g(x-1)-1)*(f(x-1)+g(x-1)-3)+12*f(x-1)-13

g(x)=(f(x-1)+g(x-1))*(f(x-1)+g(x-1)-4)+12*g(x-1)-7

here , f(0)=2,g(0)=1

if x is given how to find f(x) and g(x) when 1<=x<=10^18 and x is an non negative integer