Thanks for your reply :smile:
Going by your idea
Let p= 5, then since d / p-1 then I guess we have d= 1, 2, 4...then solving x^ d = 1 (mod 5)
for d=1, x=1
for d=2, x= 4, 6,9,11,14, ...
for d=4, x= 2, 3,4,6, 7 ...
So I am thinking atleast d...
But not sure...I did not study...