Ошибка преобразования значения varchar "МР-12" в тип данных int

USE NEW
 
IF NOT EXISTS(SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = 'TimeTable')
BEGIN
CREATE TABLE TimeTable (
FIO VARCHAR(50),
Sredn INT,
[GROUP] VARCHAR(50)
)
END
 
ELSE 
 
BEGIN
DROP TABLE TimeTable
CREATE TABLE TimeTable (
fio VARCHAR(50),
sredn INT,
[GROUP] VARCHAR(50)
)
END
--Создаем курсор
 
DECLARE @cur CURSOR,
@fio VARCHAR(50),
@avg INT,
@GROUP VARCHAR(50),
@fetch_res INT
 
SET @cur = CURSOR SCROLL 
FOR 
WITH cte_1 AS
(
SELECT PERSONS.SURNAME + ' ' + (LEFT(FIRSTNAME,1)+'.') + (LEFT(PATRONAME,1)+'.') AS fio, [GroupName].GroupName AS [GROUP], [MARK].Mark
FROM PERSONS 
JOIN STUD ON PERSONS .id_PERS = STUD.id_PERS
JOIN STUDGROUP ON STUD.id_STUD = STUDGROUP.id_STUD
JOIN [GroupName] ON STUDGROUP.id_group = [GroupName].id_group
JOIN MARK ON STUD.id_STUD = MARK.id_STUD 
JOIN SUBJECTS ON MARK.id_SUBJECTS = SUBJECTS.id_SUBJECTS 
 
WHERE [GroupName].GroupName = 4
 
--JOIN Student_Subject ON Student_Subject.id_Student = Student.id_Student 
--JOIN Subjects ON Subjects.id_Subject = Student_Subject.id_Subject 
--WHERE [Group].Course = 4 
)
SELECT   fio AS 'Ф.И.О.', AVG(Mark) AS 'Средний бал', MAX([GROUP]) AS 'Группа'  
FROM cte_1  
GROUP BY fio 
HAVING /*MIN(Mark)* > 60 and*/ AVG(Mark) BETWEEN 3 AND 4
 
--Откроем курсор
OPEN @cur
 
--Пока есть данные в курсоре - выборка циклом
while (1 = 1)
BEGIN
FETCH NEXT FROM @cur 
INTO @fio, @avg, @GROUP
SET @fetch_res = @@FETCH_STATUS
IF (@fetch_res = -1)
break;
IF (@fetch_res <> -2)
    INSERT INTO TimeTable
    VALUES (@fio, @avg, @GROUP)
END
 
--Закрываем курсор
CLOSE @cur
--Уничтожаем курсор
DEALLOCATE @cur
SELECT * FROM TimeTable
DROP TABLE TimeTable