Compilare: user.cpp: In function ‘void read()’: user.cpp:20: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void DFS_DOWN(int, int, int, int)’: user.cpp:36: warning: operation on ‘L’ may be undefined user.cpp:58: warning: operation on ‘L’ may be undefined user.cpp: In function ‘int main()’: user.cpp:183: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result