combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:27:11: 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 (res == ans.length()) ans += but[2];
| ~~~~^~~~~~~~~~~~~~~
combo.cpp:28:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
28 | else if (res == ans.length() + 1) ans += but[0];
| ~~~~^~~~~~~~~~~~~~~~~~~
combo.cpp:31:17: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
31 | if (ans.size() == N) return ans;
| ~~~~~~~~~~~^~~~
combo.cpp:32:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
32 | if (press(ans + but[0]) == ans.length() + 1) ans += but[0];
| ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
combo.cpp:33:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
33 | else if (press(ans + but[1]) == ans.length() + 1) ans += but[1];
| ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~