[板子]快读

int rd(){
    int x=0,p=1;
    char ch=getchar();
    while(ch>'9' || ch<'0'){
        if(ch=='-'){
            p=-1;
        }
        ch=getchar();
    }
    while(ch>='0' && ch<='9'){
        x=x*10+ch-'0';
        ch=getchar();
    }
    return x*p;
}