Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:18: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void query(int)’: user.cpp:67: warning: unused variable ‘f’ user.cpp: In function ‘int main()’: user.cpp:89: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:90: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:91: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:95: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:104: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:107: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:111: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result