sub.cpp: In function 'int main()': sub.cpp:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result sub.cpp:30: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result sub.cpp:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result sub.cpp:33: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result sub.cpp:52: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result sub.cpp:64: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result sub.cpp:87: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result sub.cpp:90: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result