#coding: utf-8
##yuki_279

s=[]
s=raw_input()

count_t=0
count_r=0
count_e=0

for i in xrange(len(s)):
 if s[i]=='t':
  count_t+=1
 elif s[i]=='r':
  count_r+=1
 elif s[i]=='e':
  count_e+=1
 else:
  continue

res=min(count_t,count_r,count_e/2)
print res