#!/bin/ruby
S = gets.chomp.split('')
counter = {
  't' => 0,
  'r' => 0,
  'e' => 0,
}

S.count.times do | num |
  if ['t', 'r', 'e'].include?(S[num])
    counter[S[num]] += 1
  end
end

puts [counter['t'], counter['r'], counter['e'] / 2].min