Programming a plurality of student number from the keyboard, and then outputs the tens digit number school student number is 9 (the input end of cycle 0).

#include<stdio.h>
void main()
{
long int num;
scanf("%1d",&num);
do
{
if(num/10%10==9)
printf("%1d\n",num);
scanf("%1d",&num);
}while(num!=0);
}