You're doing some kind of exam, aren't you?
If so, maybe you should fire up Photoshop and learn the material, rather than asking others to do your work.
There isn’t “a value” that will work for everything. It depends on the amplitude of the noise and the smoothness or sharpness of the edges you want to sharpen. The general process is trial-and-error to determine what values to use on an image-by-image basis.
In Lightroom, the answer is to hold down the Alt key while dragging the masking slider until only the edges show up as white, but you’re posting on the Photoshop forum so it’s unlikely that is the product you’re asking about.