combo.cpp: In function 'std::string guess_sequence(int)':
combo.cpp:48:22: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   48 |     while (ans.size()<n-1)
      |            ~~~~~~~~~~^~~~
In file included from /usr/include/c++/10/cassert:44,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:33,
                 from combo.cpp:1:
combo.cpp:63:24: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   63 |         assert(d.size()<=4*n);
      |                ~~~~~~~~^~~~~
combo.cpp:67:14: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   67 |         if (p==ans.size())
      |             ~^~~~~~~~~~~~
combo.cpp:69:14: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   69 |         if (p==ans.size()+1)
      |             ~^~~~~~~~~~~~~~
In file included from /usr/include/c++/10/cassert:44,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:33,
                 from combo.cpp:1:
combo.cpp:76:22: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   76 |     assert(ans.size()==n-1);
      |            ~~~~~~~~~~^~~~~
combo.cpp:78:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   78 |     for (int j = 0; j < z.size()-1; j++)
      |                     ~~^~~~~~~~~~~~
combo.cpp:83:14: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   83 |         if (p==ans.size()+1)
      |             ~^~~~~~~~~~~~~~
combo.cpp:47:10: warning: unused variable 'lst' [-Wunused-variable]
   47 |     char lst='-';
      |          ^~~