What is the output of the following C program ?

#includestdio.h 
   void main( ) 
{ 
        int a = 20, b=15, c=3; 
        if(ab) 
 {
        if(ac) 
  {
        printf("A is greater\n");
   }
        else
  { 
        printf(" C is greater \n");
   }
  } 
        else
  {
        if(bc)
  { 
        printf("B is greater\n");
   }
        else
  {
       printf("C is greater\n");
   }
}