# No.279 木の数え上げ
s = input()
trees = 0

while True:
    if 't' in s:
        s = s.replace('t', '', 1)
        if 'r' in s:
            s = s.replace('r', '', 1)
            if 'e' in s:
                s = s.replace('e', '', 1)
                if 'e' in s:
                    s = s.replace('e', '', 1)
                    trees += 1
                else:
                    break
            else:
                break
        else:
            break
    else:
        break

print(trees)