#include <iostream>
#include <stdlib.h>
using namespace std;



void fmzero()
{
  cerr<<"the fm can't be zero!"<<endl;
  system("PAUSE");
}  


class Fraction
{
   public:
           int fz;
           int fm;
     
           Fraction(int x=0,int y=1);
           Fraction(const Fraction&);
           Fraction &operator=(const Fraction&);
           Fraction operator+(const Fraction&);
           Fraction operator-(const Fraction&);
           Fraction operator*(const Fraction&);
           Fraction operator/(const Fraction&);
};





Fraction::Fraction(int x,int y)
{  
   if(!y)fmzero();
   fz=x;
   fm=y;
}


Fraction::Fraction(const Fraction &x)
{
   if(!x.fm)fmzero();
   fz=x.fz;
   fm=x.fm;
}   


Fraction &Fraction::operator=(const Fraction &x)
{   
    if(!x.fm)fmzero();
    fz=x.fz;
    fm=x.fm; 
    return (*this);
}


Fraction Fraction::operator+(const Fraction &x)
{
     if(!x.fm)fmzero();
     Fraction tmp;
     tmp.fm=(this->fm)*(x.fm);
     tmp.fz=(x.fm)*(this->fz)+(this->fm)*(x.fz);
     return tmp;
}



Fraction Fraction::operator-(const Fraction &x)   
{
        if(!x.fm)fmzero();
        Fraction tmp;
        tmp.fm=(this->fm)*(x.fm);
        tmp.fz=(x.fm)*(this->fz)-(this->fm)*(x.fz);
        return tmp;
}



Fraction Fraction::operator*(const Fraction &x)          
{
      if(!x.fm)fmzero();
      Fraction tmp;
      tmp.fz=(this->fz)*(x.fz);
      tmp.fm=(this->fm)*(x.fm);
      return tmp;
}



Fraction Fraction::operator/(const Fraction &x) 
{
      if((!x.fm)||(!x.fz))fmzero();
      Fraction tmp;
      tmp.fz=(this->fz)*(x.fm);
      tmp.fm=(this->fm)*(x.fz);
      return tmp;
}