C++ :

#include <bits/stdc++.h>
using namespace std;
int gcd(int x,int y)
{
	int r=x%y;
	
	while (r!=0)
	{
		
		x=y;
		y=r;
		r=x%y;
	}
	
	return y;
}
int gcl(int x,int y)
{
	return x*y/gcd(x,y);
}
int main()
{
	int x,y,x1,y1,f=0;
	char fg,fh;
	cin>>x>>fg>>y>>fh>>x1>>fg>>y1;
	//step1:通分
	x=x*(gcl(y,y1)/y);
	x1=x1*(gcl(y,y1)/y);
	y=gcl(y,y1);
	y1=y;
	//step2相加/相减
	if (fh=='+') x=x+x1;
	else x=x-x1;
	if (x<0) 
	{
		f=1;
		x=abs(x);
	}
	if (x==0) cout<<0<<endl;
	//step3:约分
	else
	{
		if (f==1) cout<<"-"; 
		cout<<x/gcd(x,y)<<"/"<<y/gcd(x,y)<<endl; 
	}
	
 	return 0;
}