combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:54:8: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
54 | if (c==ans.size()+2) ans+=c[(fc+1)%4];
| ~^~~~~~~~~~~~~~
combo.cpp:54:30: error: invalid types 'int[int]' for array subscript
54 | if (c==ans.size()+2) ans+=c[(fc+1)%4];
| ^
combo.cpp:55:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
55 | else if (c==ans.size()+1) ans+=c[(fc+2)%4];
| ~^~~~~~~~~~~~~~
combo.cpp:55:35: error: invalid types 'int[int]' for array subscript
55 | else if (c==ans.size()+1) ans+=c[(fc+2)%4];
| ^
combo.cpp:56:14: error: invalid types 'int[int]' for array subscript
56 | else ans+=c[(fc+3)%4];
| ^