Compilare: main.cpp: In function 'std::__cxx11::string getmform(std::__cxx11::string)': main.cpp:30:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<s.size(); i++) ~^~~~~~~~~ main.cpp: In function 'int main()': main.cpp:59:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<s.size()-1; i++) ~^~~~~~~~~~~ main.cpp:90:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<s.size()-1; i++) ~^~~~~~~~~~~