#include <stdio.h>

main ()
{ 
  int n,r;
  printf("Enter a Number:\n");
  scanf("%d",&n);

 r=n%9;
 
 if(r==0)
 {
 	printf("Lucky Number : 9");
 }else
 {
 	printf("Lucky Number : %d",r);
 }
 
}
     
           
Note: Need to be arranged in compiler after copied
   

 OutPut:

Enter a Number: 1239 Lucky Number : 6