Compilare: user.cpp: In function 'int get_edge(int, char)': user.cpp:12: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'void add(std::vector<char, std::allocator<char> >, int)': user.cpp:21: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'std::pair<int, int> find(std::vector<char, std::allocator<char> >)': user.cpp:38: warning: comparison between signed and unsigned integer expressions user.cpp:40: warning: comparison between signed and unsigned integer expressions user.cpp:48: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'int main()': user.cpp:37: warning: 'next' may be used uninitialized in this function user.cpp:37: note: 'next' was declared here