Compilare: main.cpp: In function 'void backtrack(int, int, int, std::string)': main.cpp:17:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 17 | for(int i=0;i+1<s.size();i+=2){ | ~~~^~~~~~~~~ main.cpp:23:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::__cxx11::basic_string<char> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 23 | for(int i=0;i<aux1.size();i++){ | ~^~~~~~~~~~~~