foo.cc: In function 'int 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.length()-1){
      |             ~~~~~^~~~~~~~~~~~~~
foo.cc:36:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   36 |             if (next.x<a.size()){
      |                 ~~~~~~^~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:45:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   45 |     scanf("%d",&n);
      |     ~~~~~^~~~~~~~~

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