Compilare: user.cpp: In function ‘void ord_dfs(int)’: user.cpp:21: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void read()’: user.cpp:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:53: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void df2(int)’: user.cpp:104: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void pre_lca()’: user.cpp:113: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void dfs(int)’: user.cpp:131: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void solve()’: user.cpp:139: warning: comparison between signed and unsigned integer expressions user.cpp:146: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:163: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result