.model small
.stack 100h

.data
  a db ?
  c dw 'you are in level $'
  d dw 'restrictin ...you are in server room $'
  e dw 'Invalid level entered $'
.code

main proc

     mov ax, @data
     mov ds, ax

  input:
     mov ah, 1
     int 21h
     ;caution without al register variable cannot hold value
     mov a, al

     mov ah, 2
     mov dl, ' '
     int 21h

      cmp a, '0'
     je levelexit
     cmp a, '1'
     je levelexit
      cmp a, '2'
     je levelexit
      cmp a, '3'
     je levelexit
      cmp a, '4'
     je levelexit
      cmp a, '5'
     je levelexit
      cmp a, '6'
     je warning


    ; jge Invalid
    jg invalid



 Invalid:
        ;LOAD EFFECTIVE ADDRESS
    mov ah, 9
    lea dx, e
    int 21h

    jmp exit


 warning:
       ;LOAD EFFECTIVE ADDRESS
    mov ah, 9
    lea dx, d
    int 21h

    jmp exit


  levelexit:
        ;LOAD EFFECTIVE ADDRESS
    mov ah, 9
    lea dx, c
    int 21h

    mov ah, 2
    mov dl, ' '
    int 21h

    mov ah, 2
    mov dl, a
    int 21h

     exit:
     ; successful termination
     mov ah, 4ch
     int 21h

    main endp
end main