C :

#include<stdio.h>
#include<math.h>
int main()
{
    char o;
    int p,q,t,i,j,m,a,b,c,d,k;
    while(scanf("%d/%d%c%d/%d",&a,&b,&o,&c,&d)!=EOF)
    {
        p=b*d;
        if(o=='+')
        q=a*d+b*c;
        if(o=='-')
            q=a*d-b*c;
        if(p==q)
            printf("1\n");
        else if(q==0)
            printf("0\n");
        else if(q%p==0)
            printf("%d\n",q/p);
        else
        {
            k=q;
            if(q<0)
                q=-q;
            else
                q=q;
                i=p;j=q;
                while(i)
                {
                    m=j%i;
                    j=i;
                    i=m;
                }
            p=p/j;k=k/j;
            printf("%d/%d\n",k,p);
            }
         }
    return 0;
}