combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:27:19: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
27 | while(s.size()<N-1) {
| ~~~~~~~~^~~~
combo.cpp:29:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
29 | if(k==s.size()) s+=c;
| ~^~~~~~~~~~
combo.cpp:30:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
30 | else if(k==s.size()+1) s+=a;
| ~^~~~~~~~~~~~
combo.cpp:33:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
33 | if(press(s+a)==s.size()+1) return s+a;
| ~~~~~~~~~~^~~~~~~~~~~~
combo.cpp:34:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
34 | if(press(s+b)==s.size()+1) return s+b;
| ~~~~~~~~~~^~~~~~~~~~~~