#coding: UTF-8

import sys
import re
import itertools
from collections import deque

### defs ###


### main ###
S = sys.stdin.readline().strip('\n')
ans=0
tcnt=0
ecnt=0
rcnt=0
for c in S:
	if(c=='t'):
		tcnt+=1
	elif(c=='r'):
		rcnt+=1
	elif(c=='e'):
		ecnt+=1
print(min(tcnt,rcnt,ecnt//2))