/in/foo.cc: In function 'void dfs(int)':
/in/foo.cc:8:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<e[p].size();++i){
              ~^~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:51:16: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
     int mid=l+r+1>>1;
             ~~~^~