Skew-symmetric matrix code help

[UtaChan]

I had to write a program that finds out whether a matrix is Skew-symmetric matrix or not...well my code is a disaster I seek help in this matter.
In which way can I write this code to make it eficient,short and smart?

this is my code (yet again it;s a disaster I know):

sstack segment stack
    dw 100h dup(?)
    sstack ends
sdata segment
   a db 0,0fch,0f8h,0eeh,4,0,0f7h,0edh,8,9,0,0ech,12h,13h,14h,0
   N db 4 

   num db 0
   count db 0
    sdata ends
scode segment
    assume ss:sstack,ds:sdata,cs:scode
    start:mov ax,sdata
    mov ds,ax
    
    mov cx,0
    mov bl,N
    mov ax,0
    mov al,N
    mul bl
    mov cl,al
    
    mov si,0
    mov di,0
    
    mov ax,0 
    mov dx,0 
    
    loop1:
 mov bx,0
 
 mov bl,a[si]
 mov bh,a[di]
 add bh,bl
 cmp bh,0
 jne not_Skew_symmetric matrix
    inc si
    mov bx,0
    mov bl,N     
    add di,bx
    inc count 
    mov bl,N
 
    cmp count,bl
    jne cont  
    inc num 
    mov bx,0
    mov bl,num
    mov di,bx
    mov count,0

    cont:      
    loop loop1      
   jmp cont2
   not_Skew_symmetric matrix:
   mov ax,0ffffh
   cont2: 
       
    mov ah,4ch
      int 21h
    scode ends
end start

Sorry about the mess >.>;
This is the part that checks the main diagoncal for 0s:

sstack segment stack
    dw 100h dup(?)
    sstack ends
sdata segment
   a db 0,0fch,0f8h,0eeh,4,0,0f7h,0edh,8,9,0,0ech,12h,13h,14h,0
   N db 4   
   col db 0
   row db 0
    sdata ends
scode segment
    assume ss:sstack,ds:sdata,cs:scode
    start:mov ax,sdata
    mov ds,ax
       
    mov cx,0
    mov bl,N
    mov ax,0
    mov al,N
    mul bl
    mov cl,al
    
    mov si,0
    mov di,0    
    mov ax,0 
    mov dx,0 
    
    loop1:    
    mov dl,row
    cmp dl,col
    jne cont1              
    cmp a[si],0
    jne diff_matrix 
   
    cont2:      
    inc si     
    mov bx,0          
    mov bl,N
    mov ax,si
    div bl  
    mov row,al
    mov col,ah       
    loop loop1
    jmp cont2
    
    diff_matrix:
    mov ax,0ffffh
    
     cont2:
    mov ah,4ch
      int 21h
    scode ends
end start

I worte the part checking for 0s first then started all over with a new idea for checking the rest....I hate these codes -.-;.