/in/foo.cc: In function 'void topu()':
/in/foo.cc:24:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for(i=0;i<v[st].size();i++)
         ~^~~~~~~~~~~~~
/in/foo.cc: In function 'int lca(int, int)':
/in/foo.cc:42:2: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
  if(a==b)return a;
  ^~
/in/foo.cc:43:3: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   for(i=17;i>=0;i--)
   ^~~
/in/foo.cc: In function 'void dfs(int)':
/in/foo.cc:62:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(i=0;i<v3[o].size();i++)
          ~^~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:92:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(j=0;j<v2[st].size();j++)
          ~^~~~~~~~~~~~~~