int main int argc char argv int double printf Please input scanf scanf

int main(int argc, char *argv[])
{
  int p,q;
  double f;
  printf("Please input p,q:\n");
  scanf("%d",&p);
  scanf("%d",&q);
  f = q>=100 ?((p+q)/(2.*q)) : (q>0 && p<20) ? (p-2*q) : (p-3*q);
  printf("f=%lf\n",f); 
  system("PAUSE");	
  return 0;
}