// c++
#include <bits/stdc++.h>
using namespace std;

int main() {
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
    return 0;
}

手动分界

// java
import java.io.*;
import java.util.Scanner;

public class Main {

    private static void redirectInput() throws FileNotFoundException { // 重定向stdin到文件
        InputStream fin = new FileInputStream("in.txt");
        System.setIn(fin);
    }

    private static void redirectOutput() throws FileNotFoundException { // 重定向stdout到文件
        OutputStream fout = new FileOutputStream("out.txt");
        PrintStream fps = new PrintStream(fout);
        System.setOut(fps);
    }

    public static void main(String[] args) throws FileNotFoundException { // test code
        redirectInput();
        redirectOutput();
        Scanner sc = new Scanner(System.in);

//        System.out.println("redirect...");
//        for (int i = 0; i < 200; ++i) System.out.println(i);

        while (sc.hasNextLine()) {
            System.out.println(sc.nextLine());
        }

    }
}