Compilare: user.cpp: In function ‘void read()’: user.cpp:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void dfs(int)’: user.cpp:28: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void write()’: user.cpp:54: warning: comparison between signed and unsigned integer expressions user.cpp:55: warning: comparison between signed and unsigned integer expressions