function! s:output()
  let this = {'lines': []}

  function! this.append(line) abort
    call add(self.lines, a:line)
  endfunction

  function! this.build() abort
    return join(self.lines, "\n")
  endfunction

  return this
endfunction

function! s:main(input) abort
  let o = s:output()

  let l = len(a:input[0])
  let c_t = l - len(substitute(a:input[0], 't', '', 'g'))
  let c_r = l - len(substitute(a:input[0], 'r', '', 'g'))
  let c_e = l - len(substitute(a:input[0], 'e', '', 'g'))

  let c_e = c_e / 2
  let r = min([c_t, c_r, c_e])

  call o.append(r)
  return o.build()
endfunction

let s:input = getline(1, '$')
enew
put =s:main(s:input)
2,$print