void foo(int const* x, int* const y) 
{ 
   int a; 
 
   *x = 5; //1 
   x = &a; //2 
   *y = 5; //3 
   y = &a; //4 
 
} 
int main() 
{ 
   int x,y; 
   foo(&x,&y); 
}