Compilare: main.cpp: In function 'long long int CheckE(std::__cxx11::string)': main.cpp:16:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i <= st.size()-1; ++i) ~~^~~~~~~~~~~~~~ main.cpp: In function 'long long int Cost(std::__cxx11::string)': main.cpp:25:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); ++i) ~~^~~~~~~~~~