Notes

№include <iostream>

using namespace std;

long gcd(long n, long d){
long gcd = 0;
long max = 0;
if(n < d){
max = n;
}else max = d;
while(max > 0){
if(n % max == 0 && d % max == 0){
gcd = max;
break;
}
max--;
}
return gcd;
}

class Rational{

long n_;
long d_;

public:

Rational(long n, long d){
n_= n;
d_= d;
}

long get_numerator() const{
return n_;
}

long get_denominator() const{
return d_;
}

Rational& set_numerator(long n){
n_ = n;
return *this;
}

Rational& set_denominator(long d){
d_ = d;
return *this;
}

Rational& add(Rational& other){
if(d == other.d){
n_+= other.n_;
}else{
n_= n_* other.d_;
other.n = other.n * d_;
n_= n_+ other.n_;
d_= d_* other.d_;
}
long div = gcd(n_, d_);
n_= n_/div;
d_= d_/div;
return *this;
}

Rational& sub(Rational& other){
if(d == other.d){
n_-= other.n_;
}else{
n_= n_* other.d_;
other.n = other.n * d_;
n_= n_- other.n_;
d_= d_* other.d_;
}
long div = gcd(n_, d_);
n_= n_/div;
d_= d_/div;
return *this;
}

Rational& mul(const Rational& other){
n_*= other.n_;
d_*= other.d_;
long div = gcd(n_, d_);
n_= n_/div;
d_= d_/div;
return *this;
}

Rational& div( Rational& other){
long val = other.n_;
other.n_= other.d_;
other.d_= val;
n_*= other.n_;
d_*= other.d_;
long div = gcd(n_, d_);
n_= n_/div;
d_= d_/div;
return *this;
}

void print() const{
cout << "(" << n << "/" << d << ")" << endl;
}

Rational operator-(void) const{
Rational result(-n_, -d_);
return result;
}
};
Rational operator-(const Rational& r1, Rational& r2){
Rational result(r1.get_numerator(), r1.get_denominator());
result.sub(r2);
return result;
}

Rational operator+(const Rational& r1, Rational& r2){
Rational result(r1.get_numerator(), r1.get_denominator());
result.add(r2);
return result;
}

Rational operator*(const Rational& r1, const Rational& r2){
Rational result(r1.get_numerator(), r1.get_denominator());
result.mul(r2);
return result;
}

Rational operator/(const Rational& r1, Rational& r2){
Rational result(r1.get_numerator(), r1.get_denominator());
result.div(r2);
return result;
}

ostream& operator<<(ostream& out, const Rational& r){
out << "(" << r.get_numerator() << "/" << r.get_denominator() << ")";
return out;
}

istream& operator>>(istream& in, Rational& r){
char ch=0;
long n=0, d, p=0;

in >> ch;
if(ch!='('){
in.clear(ios_base::badbit);
return in;
}
in >> n;
in >> ch;
if(ch!='/'){
in.clear(ios_base::badbit);
return in;
}
in >> d;
in >> ch;
if(ch!=')'){
in.clear(ios_base::badbit);
return in;
}

if(in.good()) {
r.set_numerator(n).set_denominator(d);
}
return in;
}

int main(){

Rational r1(0,0);
Rational r2(0,0);
Rational r3(0,0);

char op, eq;

while(true){
(cin >> r1) >> op >> r2 >> eq;
if(cin.bad()) {
break;
}
switch (op) {
case '+': cout << ">" << " " << r1 + r2 << endl;
cout << ">";
break;
case '-': cout << ">" << " " << r1 - r2 << endl;
cout << ">";
break;
case '*': cout << ">" << " " << r1 * r2 << endl;
cout << ">";
break;
case '/': cout << ">" << " " << r1 / r2 << endl;
cout << ">";
break;
}
}
}