foo.cc: In function ‘void dfs(int)’:
foo.cc:8:23: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
    8 |         for (int i=0;i<g[u].size();i++)
      |                      ~^~~~~~~~~~~~
foo.cc: In function ‘int main()’:
foo.cc:30:31: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   30 |                 for (int j=0;j<g[i].size();j++) cout<<g[i][j]<< ' ';
      |                              ~^~~~~~~~~~~~