alias dify {
  if $isid {
    var %dify $1
    var %hCount = $count(%dify, h)
    var %sCount = $count(%dify, s)
    var %nCount = $count(%dify, n)
    if (%hCount && %sCount && %nCount) {
      write b.txt %dify
    }
  }
  else {
    filter -fk a.txt dify *
  }
}