In figure, the $n$-channel $\text{MOSFETs}$ are identical and their current voltage characteristics are given by the following expressions:
For $V_{D S}, I_D=\left[\left(V_{G S}-1\right) V_{D S}-\frac{V^2 D S}{2}\right] m A$
For $V_{D S} \geq\left(V_{G S}-1\right),\left(V_{G S}-1\right)=\left(V_{G S}-1\right)^2 m A$
Where $V_{G S}$ and $V_{D S}$ are the gate source and drain source voltages respectively and $I_0$ is the drain current.
The current $I_{D C}$ flowing through the transistor ' $\mathrm{M}$ ' is equal to__________.