Compilare: user.cpp: In function ‘void read()’: user.cpp:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void dfs(int)’: user.cpp:42: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void prepare()’: user.cpp:56: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void dfs2(int)’: user.cpp:72: warning: comparison between signed and unsigned integer expressions user.cpp:78: warning: comparison between signed and unsigned integer expressions user.cpp:80: warning: comparison between signed and unsigned integer expressions user.cpp:91: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:103: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:104: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result