The logical operator is equal to = =, and the thinking is a bit confusing, so it seems meaningless to switch.

If (z==0)

printf("%d，%d\n "，x，(x+ 1)* 5)；

If (n==0)

printf("%d，%d\n "，x，(x- 1)* 5)；

other

Printf ("The number entered does not meet the requirements");