foo.cc: In function 'void dfs(ll, ll)':
foo.cc:24:21: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   24 |         for(ll i=0;i<to[u].size();i++){
      |                    ~^~~~~~~~~~~~~
foo.cc: In function 'void DFS(ll, ll)':
foo.cc:38:21: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   38 |         for(ll i=0;i<to[u].size();i++){
      |                    ~^~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:90:12: warning: variable 'posi' set but not used [-Wunused-but-set-variable]
   90 |         ll posi=0;
      |            ^~~~

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