istream& operator>>(istream& in, Fraction& r)
{
   int t, b;
   // Read the top
   in >> t;
   // If there is a slash, read the next number
   char c;
   in >> c;
   if (c == '/')
      in >> b;
   else
   {
      in.putback(c);
      b = 1;
   }
   r = Fraction(t, b);
   return in;
}