foo.cc: In function 'bool BFS()':
foo.cc:19:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   19 |         if (now.x==a.size()-1){
      |             ~~~~~^~~~~~~~~~~~
foo.cc:37:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   37 |             if (next.x<a.size()&&a[next.x]!=' '){
      |                 ~~~~~~^~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:47:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   47 |     scanf("%d",&n);
      |     ~~~~~^~~~~~~~~

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