xor1.cpp: In function 'int main()': xor1.cpp:11: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result xor1.cpp:12: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result xor1.cpp:16: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result