check_is_number:
	cmp al, 48
	jl .not_number
	cmp al, 57
	jg .not_number
	stc
	ret
.not_number:
	clc
	ret

check_is_letter:
	cmp al, 65
	jl .not_letter
	cmp al, 122
	jg .not_letter
	cmp al, 90
	jg .maybe_not_letter
	stc
	ret
.maybe_not_letter:
	cmp al, 97
	jl .not_letter
	stc
	ret
.not_letter:
	clc
	ret