S = input()

T = 0
R = 0
E = 0
tree = 0

for s in S:
    if (s == 't'):
        T += 1
    elif (s == 'r'):
        R += 1
    elif (s == 'e'):
        E += 1
    
    if (T >= 1 and R >= 1 and E >= 2):
        tree += 1
        T -= 1
        R -= 1
        E -= 2
    
print(tree)