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:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void dfs()’: user.cpp:39: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void write()’: user.cpp:64: warning: comparison between signed and unsigned integer expressions user.cpp:69: warning: comparison between signed and unsigned integer expressions