Compilare: user.cpp: In function ‘void read()’: user.cpp:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void dfs(int)’: user.cpp:43: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void prepare()’: user.cpp:57: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void dfs2(int)’: user.cpp:73: warning: comparison between signed and unsigned integer expressions user.cpp:83: warning: comparison between signed and unsigned integer expressions user.cpp:92: warning: comparison between signed and unsigned integer expressions user.cpp:101: warning: comparison between signed and unsigned integer expressions user.cpp:104: warning: comparison between signed and unsigned integer expressions user.cpp:110: warning: comparison between signed and unsigned integer expressions user.cpp:120: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:132: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:133: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result