foo.cc: In function 'bool check(long long int)':
foo.cc:17:18: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<node>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   17 |     for(ll i=0; i<edge[x].size(); i++){
      |                 ~^~~~~~~~~~~~~~~

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