foo.cc: In function 'int main()':
foo.cc:53:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<state.size();j++){
               ~^~~~~~~~~~~~~
foo.cc:55:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int k=0;k<state.size();k++){
                ~^~~~~~~~~~~~~
foo.cc:68:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<state.size();i++)
              ~^~~~~~~~~~~~~

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