goroutines getting stuck during execution

I am trying to implement producer-consumer where teacher will teach subjects and students will study them.In my main file,I have started goroutines:

func main(){    w:=WhiteBoard{counter:-1}       var x []Student=[]Student{Student{name: "Aditya",w:&w},Student{name: "Abhinav",w:&w},Student{name: "Devansh",w:&w}}    var t Teacher =Teacher{w:&w,subjects: []string{"Math","END"}}    mu=new(sync.Mutex)    wg= new(sync.WaitGroup)    for _,student:=range x{        student.attendence()    }    t.teach() //Teacher starts teaching ->goroutines    //Add Student to the waitgroup    for _,student:=range x{        go student.w.write(student.name)  //student starts writing -> goroutines     }    wg.Wait()}

Whiteboard is a shared data resource from which teachers will write and students will read:

type WhiteBoard struct {    noOfStudents int    counter      int    subject      string}func (w *WhiteBoard) write(subject string){    mu.Lock()    for w.counter!=-1{    }    if subject=="END"{        defer wg.Done()        done<-true        w.counter++        mu.Unlock()        fmt.Println("Teacher is ending the class: ",subject)        return    }    w.subject=subject    fmt.Println("Teacher is teaching this subject: ",subject)    w.counter++    student_start<-true    mu.Unlock()    defer wg.Done()}func (w *WhiteBoard) read(name string){    for{        select {            case <-done:                defer wg.Done()                return            case <-student_start:                fmt.Println(name+" is studying this subject: ",w.subject)                w.counter++                if w.counter==w.noOfStudents{                    w.counter=-1                }         }    }}

Now the issue is that when i only run with 1 teacher and 1 student my output looks correct:

-> % go run main.goAditya  has given their attendenceTeacher is teaching this subject:  MathAditya is studying this subject:  MathTeacher is ending the class:  END

But with multiple students,the gorutines get stuck and don't exit

-> % go run main.goAditya  has given their attendenceAbhinav  has given their attendenceDevansh  has given their attendenceTeacher is teaching this subject:  MathDevansh is studying this subject:  Math//Nothing prints after this

I am not sure why this is happening??Here's the full code- https://go.dev/play/p/z3nJZUmEiI8