tric.cpp: In function 'void PerfectEliminationOrder()': tric.cpp:31: warning: comparison between signed and unsigned integer expressions tric.cpp: In function 'int main()': tric.cpp:56: warning: comparison between signed and unsigned integer expressions tric.cpp:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result tric.cpp:42: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result tric.cpp:45: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result tric.cpp:47: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result