There are 20 questions in a math test, and it is stipulated that 2 points will be awarded for each correct answer, 1 point will be deducted for each incorrect answer, and no points will be awarded for unanswered questions. After the exam, Xiao Ming scored 23 points in total. He wondered how many questions he got wrong, but only remembered that the number of unanswered questions was an even number. Please help Xiao Ming calculate how many questions he got wrong.
一次数学考试共有20道题，规定答对一题得2分，答错一题扣1分，未答的题不计分．考试结束后，小明共得23分．他想知道自己做错了几道题，但只记得未答的题的数目是个偶数．请你帮助小明计算一下，他答错了多少道题．
<result>3</result>