char buf[16 * 1024 * 1024 + 5]; // 10 MiB Buffer  
int curpos = 0, iseof;  
int nextInt()  
{
    int ret = 0;
    if (iseof) return 0;
    while (!('0' <= buf[curpos] && buf[curpos] <= '9')) 
    {
        if (buf[curpos] == 0)
        {
            if (fgets(buf, 16 * 1024 * 1024, stdin) == NULL) iseof = true;
            curpos = 0;
            continue;
        }
        curpos++;
    }
    int flg = 0;
    if (curpos && buf[curpos - 1] == '-') flg = -1;
    else flg = 1;
    while ('0' <= buf[curpos] && buf[curpos] <= '9')
    {
        ret = ret * 10 + (buf[curpos] - '0');
        curpos++;
    }
    return ret * flg;
}

读入1M个有符号整数(10484128字节,每行1000个,一共1000行)用时80MS