# your code goes here

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

str.size.times do |i|
	c=str[i]
	case c
	when 't'
		t+=1
	when 'r'
		r+=1
	when 'e'
		e+=1
	else
	end
end
as=[t,r,e.to_i/2]
puts as.min