Question 4
There are $1991$ students standing in a circle, facing inward, to play the following counting game. Each student says one number in turn clockwise, starting at a student $A$. The numbers said are $1,2,3$, repeated in that order. A student who says $2$ or $3$ must leave the circle immediately. The last remaining student receives a prize. Counting clockwise from $A$, who first says $1$, which starting position should a student choose to win?