TeX中的引号

在TeX中，左双引号是“”，右双引号是“''”。输入一篇包含双引号的文章，你的任务是把它转换为TeX的格式。 样例输入： "To be ro not to be,"quoth the Bard,"that is the question". 样例输出：To be or not to be,''quoth the Bard,``that is the question''.

import java.util.Scanner;

public class Main {
    
    public static void main(String[] args) {
        
        Scanner in = new Scanner(System.in);
        boolean mark = true;
        while(in.hasNextLine()) {
            
            String str = in.nextLine();
            for(int i = 0; i < str.length(); i++) {
                
                if(str.charAt(i) == '"') {
                    
                    if(mark) {
                        
                        System.out.print("``");
                        mark = false;
                    }else {
                        
                        System.out.print("''");
                        mark = true;
                    }
                }else {
                    
                    System.out.print(str.charAt(i));
                }
            }
            System.out.println();
        }
    }
}