combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:13:24: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
13 | while(pre.size() + 2 <= N) {
| ~~~~~~~~~~~~~~~^~~~
combo.cpp:20:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
20 | if(k == pre.size()+0) pre += toL[2];
| ~~^~~~~~~~~~~~~~~
combo.cpp:21:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
21 | if(k == pre.size()+1) pre += toL[0];
| ~~^~~~~~~~~~~~~~~
combo.cpp:22:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
22 | if(k == pre.size()+2) pre += toL[1];
| ~~^~~~~~~~~~~~~~~
combo.cpp:24:17: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
24 | if(pre.size() != N) {
| ~~~~~~~~~~~^~~~