s = input()

t_count = 0
r_count = 0
e_count = 0

for char in s:
    if char == 't':
        t_count += 1
    elif char == 'r':
        r_count += 1
    if char == 'e':
        e_count += 1

print(min([t_count, r_count, e_count//2]))