Compilare: user.cpp: In function ‘std::string bits(int, int)’: user.cpp:22:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(s.size() < n) { ^ user.cpp: In function ‘bool containsAll(std::string, const std::vector<std::basic_string<char> >&)’: user.cpp:29:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a.size(); i++) { ^ user.cpp: At global scope: user.cpp:48:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main() { ^