分式运算模板

ll gcd(ll a,ll b)
{
    if(b==0)
    {
        return a;
    }else
    {
        return gcd(b,a%b);
    }

}
ll ABS(ll x) {
    return x<0 ? -x : x;
}
struct F {
    ll num,den;// fenzi -> num  fenmu-> den
    F(ll num=0,ll den=1) {
        if(den<0) num=-num,den=-den;
        ll g = gcd(ABS(num),den);
        this->num = num/g;
        this->den = den/g;
    }
    F operator+(const F &o)const {
        return F(num*o.den + den*o.num, den*o.den);
    }
    F operator*(const F &o)const {
        return F(num*o.num , den*o.den);
    }
    F operator/(const F &o) const {
        return F(num*o.den,den*o.num);
    }
};