Compilare: user.cpp: In member function ‘void Tree::dfs(int)’: user.cpp:80:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i > d.size()) exit(0); ~~^~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:104:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:109:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &val[i]); ^ user.cpp:116:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &u); ^