/in/foo.cc: In function 'void dfs(int, int)':
/in/foo.cc:21:17: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(biao[zbl[i]]<ans)f=i;
                 ^
/in/foo.cc:22:26: warning: array subscript has type 'char' [-Wchar-subscripts]
   ans=min(ans,biao[zbl[i]]);
                          ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:33:35: warning: array subscript has type 'char' [-Wchar-subscripts]
  for(int i=1;i<=lg;i++)biao[cng[i]]=i;
                                   ^
/in/foo.cc: In function 'void dfs(int, int)':
/in/foo.cc:25:5: warning: 'f' may be used uninitialized in this function [-Wmaybe-uninitialized]
  dfs(l,f-1);
  ~~~^~~~~~~