Compilare: user.cpp: In function ‘void read()’: user.cpp:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void dfs(int)’: user.cpp:32: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void write()’: user.cpp:66: warning: comparison between signed and unsigned integer expressions user.cpp:67: warning: comparison between signed and unsigned integer expressions