Compilare: user.cpp: In function ‘void Solve()’: user.cpp:56:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<letters.size(); ++i) ^ user.cpp:66:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<Words.size(); ++i) ^ user.cpp:72:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<Words.size(); ++i) ^ user.cpp: In function ‘bool cmp(std::string, std::string)’: user.cpp:50:1: warning: control reaches end of non-void function [-Wreturn-type] } ^