onu2.cpp: In function 'int main()': onu2.cpp:48: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result onu2.cpp:49: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result onu2.cpp:51: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result onu2.cpp:55: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result