inputer = input()

t_count = inputer.count('t')
t_count = int(inputer.count('t')*2)
r_count = inputer.count('r')
r_count = int(inputer.count('r')*2)
e_count = inputer.count('e')

if t_count<r_count:
	result = t_count
elif t_count>r_count:
	result = r_count
elif t_count==r_count:
	result = t_count

if result >e_count:
	result = int(e_count/2)
elif result <e_count or result ==e_count:
	result = int(result/2)

print(result)