foo.cc: In function 'bool OK()':
foo.cc:16:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   16 |  return Next.x >= 0 && Next.x < str.size() && str[Next.x] != ' ';
      |                        ~~~~~~~^~~~~~~~~~~~
foo.cc: In function 'int BFS()':
foo.cc:30:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   30 |   if (now.x == str.size() - 1)
      |       ~~~~~~^~~~~~~~~~~~~~~~~
foo.cc:35:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   35 |   else if (now.x > str.size() - 1)
      |            ~~~~~~^~~~~~~~~~~~~~~~

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