pipe.cpp: In function 'int main()': pipe.cpp:14: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result pipe.cpp:15: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result pipe.cpp:16: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result pipe.cpp:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result pipe.cpp:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result pipe.cpp:12: warning: 'lmin' may be used uninitialized in this function