foo.cc:24:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   24 | main()
      |      ^
foo.cc: In function 'int main()':
foo.cc:49:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   49 |   for(int i=0;i<ve[cur].size();i++)
      |               ~^~~~~~~~~~~~~~~
foo.cc:72:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   72 |   for(int i=0;i<fan[cur].size();i++)
      |               ~^~~~~~~~~~~~~~~~

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