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:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘int bfs(std::vector<int, std::allocator<int> >)’: user.cpp:37: warning: comparison between signed and unsigned integer expressions user.cpp:46: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void solve()’: user.cpp:69: warning: comparison between signed and unsigned integer expressions