foo.cc: In function 'int dfs(int, long long int)':
foo.cc:28:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<e[nw].size();i++){
                 ~^~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:47:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf(" %lld",&ar[i]);
         ~~~~~^~~~~~~~~~~~~~~~

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