combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:38:21: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
38 | while (S.length() < N - 1){
| ~~~~~~~~~~~^~~~~~~
combo.cpp:41:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
41 | if (coins == S.length() + 1){
| ~~~~~~^~~~~~~~~~~~~~~~~
combo.cpp:44:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
44 | else if (coins == S.length() + 2){
| ~~~~~~^~~~~~~~~~~~~~~~~
combo.cpp:47:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
47 | else if (coins == S.length() + 0){
| ~~~~~~^~~~~~~~~~~~~~~~~
combo.cpp:57:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
57 | if (press(S + legal_chars[0]) == S.length() + 1){
| ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
combo.cpp:60:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
60 | if (press(S + legal_chars[1]) == S.length() + 1){
| ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~