s = input()
#s = list(s)
#x = Counter(s)
x = [0]*3
for i in s:
    if i == "t":
        x[0] += 1
    elif i == "r":
        x[1] += 1
    elif i == "e":
        x[2] += 1
x[2] //= 2
print(min(x))