# -*- coding: utf-8 -*-

S = input()

t_num = r_num = e_num = 0

for c in S:
    if c == 't':
        t_num += 1
    elif c == 'r':
        r_num += 1
    elif c == 'e':
        e_num += 1

e_num //= 2

print(min(t_num, r_num, e_num))