trip.cpp: In function 'void BDFS(int)': trip.cpp:124: warning: comparison between signed and unsigned integer expressions trip.cpp: In function 'void make_path2()': trip.cpp:142: warning: comparison between signed and unsigned integer expressions trip.cpp: In function 'void read()': trip.cpp:151: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result trip.cpp:152: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result trip.cpp:153: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result trip.cpp:156: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result