Compilare: main.cpp: In function 'int Cost_e(std::__cxx11::string)': main.cpp:21:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<s.size(); i++) ~^~~~~~~~~ main.cpp: In function 'int Cost_String(std::__cxx11::string)': main.cpp:39:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); i++) ~~^~~~~~~~~~