gxor.cpp: In function 'void read()': gxor.cpp:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result gxor.cpp:34: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result gxor.cpp:38: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result gxor.cpp: In function 'int main()': gxor.cpp:124: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result