RT，不使用的时候没问题，一使用就 CE

#include <cctype>
#include <cstdio>

namespace fastio
{
    template<typename T>
    void readone(T& a)
    {
        bool flag = 0;
        char c;
        while (!isdigit(c = getchar())) flag |= c == '-';
        a = c ^ 48;
        while (isdigit(c = getchar())) a = (a << 1) + (a << 3) + (c ^ 48);
        if (flag) a = -a;
    }
    
    template<typename T, typename... Args>
    void read(T& a, Args&... b) { readone(a); read(b...); } // Problem
}
using fastio::read;

int main()
{
    int a;
    int b;
    // read(a, b);
}