S = input()
t, r, e = 0

for value in S:
	if value == 't':
		t += 1
	elif value == 'r':
		r += 1
	elif value == 'e':
		e += 1

if (t <= r and e//2 <t) or (t > r and e//2 < r):
	print(e//2)
elif(t<= r):
	print(t)
else:
	print(r)