读入优化！

两种，不知道两种谁快。。。

inline char nc() {
    static char buf[100000], *p1 = buf, *p2 = buf;
    return p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, 100000, stdin), p1 == p2) ? EOF : *p1++;
}
inline int _read() {
    char ch = nc(); int sum = 0;
    while (!(ch >= '0'&&ch <= '9'))ch = nc();
    while (ch >= '0'&&ch <= '9')sum = sum * 10 + ch - 48, ch = nc();
    return sum;
}

namespace fastIO {
#define BUF_SIZE 100000
    bool IOerror = 0;
    inline char nc()
    {
        static char buf[BUF_SIZE], *p1 = buf + BUF_SIZE, *pend = buf + BUF_SIZE;
        if ( p1 == pend )
        {
            p1    = buf;
            pend    = buf + fread( buf, 1, BUF_SIZE, stdin );
            if ( pend == p1 )
            {
                IOerror = 1;
                return(-1);
            }
        }
        return(*p1++);
    }


    inline bool blank( char ch )
    {
        return(ch == ' ' || ch == '
' || ch == '
' || ch == '	');
    }


    inline void read( int &x )
    {
        char ch;
        while ( blank( ch = nc() ) )
            ;
        if ( IOerror )
            return;
        for ( x = ch - '0'; (ch = nc() ) >= '0' && ch <= '9'; x = x * 10 + ch - '0' )
            ;
    }


#undef BUF_SIZE
};
using namespace fastIO;