5. Given the set $M=\{z|| z-1 \mid \leqslant 1, z \in \mathbf{C}\}, N=\left\{z \left\lvert\, \arg z \geqslant \frac{\pi}{4}\right., z \in \mathbf{C}\right\}$, then the area of the figure represented by $M \cap N$ in the complex plane is $\qquad$ .
5. $S=\frac{3}{4} \pi-\frac{1}{2}$