str = gets.chomp
t = 0
r = 0
e = 0

str.chars do |c|
  if c == "t"
    t += 1
  elsif c == "r"
    r += 1
  elsif c == "e"
    e += 1
  end
end

ary = [t, r, e/2]

if ary.sort[0] < 1
  puts 0
else
  puts ary.sort[0]
end