graf.cpp: In function 'void dfs(int)': graf.cpp:24: warning: comparison between signed and unsigned integer expressions graf.cpp: In function 'int main()': graf.cpp:48: warning: comparison between signed and unsigned integer expressions graf.cpp:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result graf.cpp:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result graf.cpp:36: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result graf.cpp:39: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result