Can anyone solve this, not rlly sure how 2

Consider the complex numbers in the complex plane below:

For each of the complex numbers
$$s, t, u, v, w, z,$$ figure out the value of $n$ such that the complex number is a primitive $n$th root of unity, and enter these values of $n$ in the order above. If any of these complex numbers aren't roots of unity, enter $?$ for it.