combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:16:21: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
16 | while(ans.length()<N-2){
| ~~~~~~~~~~~~^~~~
combo.cpp:26:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
26 | if (press(ans+letters[0])==ans.length()+1) ans+=letters[0];
| ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~
combo.cpp:27:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
27 | if (press(ans+letters[1])==ans.length()+1) ans+=letters[1];
| ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~
combo.cpp:28:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
28 | if (press(ans+letters[2])==ans.length()+1) ans+=letters[2];
| ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~