BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); 
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(System.out));
String[] s1 = reader.readLine().split(" ");
n = Integer.parseInt(s1[0]);
换行 writer.write("\n");
写数字 writer.write(Integer.toString(整形数字));
结尾必须加上writer.flush();