The output of a continuous-time system y(t) is related to its input x(t) as y(t) = x(t) + $\frac{1}{2}$x(t-1). If the Fourier transforms of x(t) and y(t) are x($\omega$) and y($\omega$) respectively. and |x(0)|$^2$ = 4, the value of |y(0)|$^2$ is $\_\_\_\_$