Compilare: main.cpp: In function 'void insert(std::__cxx11::string)': main.cpp:26:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); i++) { ~~^~~~~~~~~~ main.cpp: In function 'void remove(std::__cxx11::string)': main.cpp:39:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); i++) { ~~^~~~~~~~~~ main.cpp: In function 'int aparitii(std::__cxx11::string)': main.cpp:48:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size() && v != -1; i++) { ~~^~~~~~~~~~ main.cpp: In function 'int prefix(std::__cxx11::string)': main.cpp:57:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); i++) { ~~^~~~~~~~~~