template <typename T>
bool read_int(T &x) {
    bool start = false , neg = false;
    T ret = 0;
    for (char r; r = getchar(); ) { 
        if (r == '-') neg = true;
        else if ((r < '0' || r > '9'))
            if (start) return false; else continue;
        else 
            ret += r - '0';

        if (start) ret *=10;
        start = true;
    }   
    return x = (neg ? -ret : ret), true;
}
template <typename T, typename... Tnext> 
bool read_int(T &x, Tnext... next)
{
    read_int(next...);
}