on getCommonPath (pathes, sep)
  _player.itemDelimiter = sep

  -- find length of shortest path (in terms of items)
  commonCnt = the maxInteger
  repeat with p in pathes
    if p.item.count<commonCnt then commonCnt=p.item.count
  end repeat

  pathCnt = pathes.count
  repeat with i = 1 to commonCnt
    repeat with j = 2 to pathCnt
      if pathes[j].item[i]<>pathes[j-1].item[i] then
        return pathes[1].item[1..i-1]
      end if
    end repeat
  end repeat
  return pathes[1].item[1..commonCnt]
end