SYS_EXIT equ 1
SYS_READ equ 3
SYS_WRITE equ 4
STDIN equ 0
STDOUT equ 1

segment .data
  msg1 db "Enter the first number: ", 0xA, 0xD
  len1 equ $ - msg1

  msg2 db "Enter the second number: ", 0xA, 0xD
  len2 equ $ - msg2

  msg3 db "Sum: "
  len3 equ $ - msg3

segment .bss
  num1 resb 2
  num2 resb 2
  res resb 1

section .text
  global _start

_start:
  mov eax, SYS_WRITE
  mov ebx, STDOUT
  mov ecx, msg1
  mov edx, len1
  int 0x80

  mov eax, SYS_READ
  mov ebx, STDIN
  mov ecx, num1
  mov edx, 2
  int 0x80

  mov eax, SYS_WRITE
  mov ebx, STDOUT
  mov ecx, msg2
  mov edx, len2
  int 0x80

  mov eax, SYS_READ
  mov ebx, STDIN
  mov ecx, num2
  mov edx, 2
  int 0x80

  mov eax, SYS_WRITE
  mov ebx, STDOUT
  mov ecx, msg3
  mov edx, len3
  int 0x80

  mov eax, [num1]
  sub eax, '0'

  mov ebx, [num2]
  sub ebx, '0'

  add eax, ebx

  add eax, '0'

  mov [res], eax

  mov eax, SYS_WRITE
  mov ebx, STDOUT
  mov ecx, res
  mov edx, 1
  int 0x80

exit:
  mov eax, SYS_EXIT
  xor ebx, ebx
  int 0x80