Compilare: user.cpp: In function ‘int main()’: user.cpp:19:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fi,"%d", &n); ^ user.cpp:21:28: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fi,"%x", &x); ^ user.cpp:25:26: warning: ‘root’ may be used uninitialized in this function [-Wmaybe-uninitialized] chainz = n, dfs(root); ^