A group of 268 268 students are surveyed about their ability to speak Mandarin, Korean, and Japanese. There are 37 37 students who do not speak any of the three languages surveyed. Mandarin is spoken by 174 174 of the students, Japanese is spoken by 139 139 of the students, and Korean is spoken by 112 112 of the students. The survey results also reflect that 102 102 students speak both Mandarin and Japanese, 81 81 students speak both Mandarin and Korean, and 71 71 students speak both Japanese and Korean. How many students speak all three languages