cartonase.cpp: In function 'void read()': cartonase.cpp:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result cartonase.cpp:13: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result cartonase.cpp: In function 'int main()': cartonase.cpp:27: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result cartonase.cpp:28: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result cartonase.cpp:29: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result