arbsum.cpp: In function 'void dfs(int)': arbsum.cpp:13: warning: comparison between signed and unsigned integer expressions arbsum.cpp:18: warning: comparison between signed and unsigned integer expressions arbsum.cpp:20: warning: comparison between signed and unsigned integer expressions arbsum.cpp: In function 'int main()': arbsum.cpp:28: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result arbsum.cpp:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result arbsum.cpp:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result arbsum.cpp:34: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result arbsum.cpp:38: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result