In a study about intervention on smoking, 50 participants a…

 In a study about intervention on smoking, 50 participants are recruited, consisting 25 non-smokers. All people watched an emotive video showing the death from smoking-related cancers have on families. After two days, these people are asked if they remained smokers or non-smokers.  We plan to conduct a McNemar Test, and n = 50 is a large sample.   What’s the value of MN test stat ?