https://stackoverflow.com/questions/7271939/warning-ignoring-return-value-of-scanf-declared-with-attribute-warn-unused-r/13390863리턴값무시하면 안된대
https://stackoverflow.com/questions/7271939/warning-ignoring-return-value-of-scanf-declared-with-attribute-warn-unused-r/13390863
리턴값
무시하면 안된대