If $$\frac{cos\pi}{4}-\frac{tan\pi}{4}=x$$, then x is

A

$$\frac{\sqrt{3}+4}{2\sqrt{3}}$$

B

$$\frac{2\sqrt{2}-1}{2}$$

C

$$\frac{1-\sqrt{2}}{\sqrt{2}}$$

D

$$\frac{5}{\sqrt{3}}$$