Compilare: user.cpp: In function ‘int main()’: user.cpp:72:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=A.length(); i<B.length(); ++i) ^ user.cpp:90:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<sol.size(); ++i) ^