str = gets.to_s
a = Array.new(3, 0)
str.length.times do |i|
    if str[i] == "t"
        a[0] += 1
    elsif str[i] == "r"
        a[1] += 1
    elsif str[i] == "e"
        a[2] += 1
    end
end
a[2] /= 2
a.sort!
puts a[0]