char Gt(){return (p1==p2&&(p2=(p1=buf)+fread(buf,1,buf_size,stdin),p1==p2))?EOF:*p1++;}
struct Fast_IO{
    Fast_IO&operator>>(std::string&S){
        S="";char ch=Gt();
        while (!isalpha(ch)) ch=Gt();
        while ( isalpha(ch)) S.push_back(ch),ch=Gt();
        return*this;
    }
    Te Fast_IO&operator>>(T&ret){
        ret=0;int f=1;char ch=Gt();
        while (!isdigit(ch)){if(ch=='-') f=-f;ch=Gt();}
        while ( isdigit(ch)) ret=(ret<<3)+(ret<<1)+(ch^48),ch=Gt();
        return ret*=f,*this;
    }
}fin;

如题，我这么读交洛谷上就挂了，但是改成cin直接A了。而且我本地Windows对拍也没有问题，求大佬解答。。。