Compilare: user.cpp: In function ‘void dfs_visit(int)’: user.cpp:27: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:57: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:61: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result