diff.cpp: In function 'int main()': diff.cpp:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result diff.cpp:13: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result diff.cpp:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result diff.cpp:15: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result diff.cpp:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result diff.cpp:43: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result