s = input()

d = {}
for i in s:
    if not i in d:
        d[i] = 1
    else:
        d[i] += 1

md = {'t': 1, 'r': 1, 'e': 2}

l = []
for i in md:
    l.append(d[i] // md[i])

print(min(l))