S = gets.chomp
counter = [0, 0, 0]

S.each_char do |s|
  counter[0] += 1 if s == 't'
  counter[1] += 1 if s == 'r'
  counter[2] += 1 if s == 'e'
end

puts [counter[0], counter[1], counter[2] / 2].min