S = input()

strt = 0
strr = 0
stre = 0
for i in range(len(S)):
    if S[i] == "t":
        strt += 1
    if S[i] == "r":
        strr += 1
    if S[i] == "e":
        stre += 1

count = 0
while strt >= 1 and stre >= 1 and stre >= 2:
    count += 1
    strt -= 1
    strr -= 1
    stre -= 2

print(count)