+#define MIN_ENVELOPE_XSIZE 1
+#define MIN_ENVELOPE_YSIZE 1
+#define MAX_ENVELOPE_XSIZE 30
+#define MAX_ENVELOPE_YSIZE 20
+#define MAX_ENVELOPE_TEXT_LEN (MAX_ENVELOPE_XSIZE * MAX_ENVELOPE_YSIZE)
+#define MIN_CHANGE_PAGES 1
+#define MAX_CHANGE_PAGES 10