Eroare de compilare: user.cpp: In function ‘int main()’: user.cpp:20:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a.length(); ++i) { ^ user.cpp:24:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < b.length(); ++i) { ^ user.cpp:27:5: error: ‘cerr’ was not declared in this scope cerr << s; ^ user.cpp:45:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (z[i] >= a.length()) { ^ user.cpp:49:5: error: ‘cout’ was not declared in this scope cout << sol.size() << "\n"; ^