# codeing=utf-8:

s = str(input())

e = s.count("e") // 2
t = s.count("t")
r = s.count("r")

if t >= e and r >= e:
    print(e)
elif t >= e and r < e:
    print(r)
elif t < e and r >= e:
    print(t)
else:
    print(0)