Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:21: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main(int, char**)’: user.cpp:59: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:60: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:62: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:68: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:69: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result