combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:18:22: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
18 | while (res.size()!=N){
| ~~~~~~~~~~^~~
combo.cpp:24:28: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
24 | while (res.size()!=N){
| ~~~~~~~~~~^~~
combo.cpp:39:23: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
39 | if (res.size()==N) break;
| ~~~~~~~~~~^~~