package com.company;

import java.util.Scanner;

public class Main {
    public static Scanner scan = new Scanner(System.in);

    public static void main(String[] args) {
        StringBuilder line = inputLine();
        int amountOfWords = findAmountOfWords(line);
        StringBuilder[] arrOfWords = new StringBuilder[amountOfWords];
        for (int i = 0; i < arrOfWords.length; i++) {
            arrOfWords[i] = new StringBuilder("");
        }
        createArrOfWords(arrOfWords, line);
        line.delete(0, line.length());
        swapWords(arrOfWords, line);
        System.out.println(line);
        scan.close();
    }

    public static StringBuilder inputLine() {
        boolean isIncorrect;
        String sourceLine;
        do {
            isIncorrect = false;
            sourceLine =  scan.nextLine();
            if (sourceLine.isEmpty()) {
                System.out.println("Line is empty");
                isIncorrect = true;
            }
        } while (isIncorrect);
        return new StringBuilder(sourceLine);
    }

    public static int findAmountOfWords(StringBuilder line) {
        int amountOfWords = 1;
        for (int i = 0; i < line.length(); i++) {
            if (line.charAt(i) == ' ') {
                amountOfWords++;
            }
        }
        return amountOfWords;
    }

    public static void createArrOfWords(StringBuilder[] arrOfWords, StringBuilder line ) {
        int j = 0;
        for (int i = 0; i < line.length(); i++) {
            if (line.charAt(i) != ' ') {
                arrOfWords[j].append(line.charAt(i));
            } else {
                j++;
            }
        }
    }

    public static void swapWords(StringBuilder[] arrOfWords, StringBuilder line) {
        for (int i = 0; i < arrOfWords.length - 1; i += 2) {
            line.append(arrOfWords[i + 1]).append(" ");
            line.append(arrOfWords[i]).append(" ");
        }
    }
}