Compilare: user.cpp: In function ‘int find_min_meeting_fuel(std::string)’: user.cpp:127:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < word.size(); ++i) { ^ user.cpp:131:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int length = 1; length < word.size(); ++length) ^ user.cpp:132:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < word.size() - length; ++i) ^ user.cpp:133:52: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = i + length; j < word.size(); ++j) ^