s = input()
t_count = 0
r_count = 0
e_count = 0
for i in range(len(s)):
    if s[i] == "t":
        t_count += 1
    elif s[i] == "r":
        r_count += 1
    elif s[i] == "e":
        e_count += 1
print(min(t_count, r_count, e_count//2))