text: template<class T>
  class fraction {
  	int n, d;
  
  	fraction(a) : n(a), d(1) {}
  	fraction(a, b) : n(a), d(b) {}
  	fraction(const PrimeSieve&) = default;
  	fraction(PrimeSieve&&) = default;
  	fraction& operator=(const PrimeSieve&) = default;
  	fraction& operator=(PrimeSieve&&) = default;
  
  	fraction& operator + (const fraction& x) {
  
  	}
  };
  