bus.cpp: In function 'void dfs(int)': bus.cpp:20: warning: comparison between signed and unsigned integer expressions bus.cpp: In function 'int main()': bus.cpp:34: warning: comparison between signed and unsigned integer expressions bus.cpp:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result bus.cpp:30: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result bus.cpp:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result bus.cpp:35: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result