fread

快速读入？ 不知道 反正只是贴过来的

以后或许会用到？

#define FI(n) FastIO::read(n)

namespace FastIO {
    const int SIZE =  << ;
    char buf[SIZE], obuf[SIZE], str[];
    int bi = SIZE, bn = SIZE, opt;
    int read(char *s) {
        while (bn) {
            for (; bi < bn && buf[bi] <= ' '; bi++);
            if (bi < bn) break;
            bn = fread(buf, , SIZE, stdin);
            bi = ;
        }
        int sn = ;
        while (bn) {
            for (; bi < bn && buf[bi] > ' '; bi++) s[sn++] = buf[bi];
            if (bi < bn) break;
            bn = fread(buf, , SIZE, stdin);
            bi = ;
        }
        s[sn] = ;
        return sn;
    }
    bool read(int& x) {
        int n = read(str), bf;

        if (!n) return ;
        int i = ; if (str[i] == '-') bf = -, i++; else bf = ;
        for (x = ; i < n; i++) x = x *  + str[i] - '';
        if (bf < ) x = -x;
        return ;
    }
};

//int n; FI(n);