40230112081 is done. !

Answers/40230112081/Admins.txt

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+40230112081,Masoud,9121231234,admin,Masoud
+40230112081,Amir1,9120719012,admin,1234
+1234512345,krm,9112342345,admin,1234

Answers/40230112081/Book.java

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+
+
+public class Book {
+    private String id;
+    private String title;
+    private String author;
+    private String description;
+    private String status;
+    private int existence;
+
+    // constructor
+    public Book(String id,String title,String author,String description,String status,int existence)
+    {
+        this.id = id;
+        this.title = title;
+        this.author = author;
+        this.description = description;
+        this.status  = status;
+        this.existence = existence;
+    }
+
+    // getters
+    public String getId() { return this.id; }
+    public String getTitle() { return this.title; }
+    public String getAuthor() { return this.author; }
+    public String getDescription() { return this.description; }
+    public String getStatus() { return this.status; }
+    public int getExistence() { return this.existence; }
+
+    // setter
+    public void change_status(String new_stat) {
+        this.status = new_stat;
+    }
+
+    public void inc_existence(){
+        this.existence++;
+    }
+}

Answers/40230112081/Books.txt

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+1,Math,Salehi,Calc,available,1
+3,Book1,Author1,Desc1,available,1