aaa = raw_input()
ans = 0
a = 0
b = 0
c = 0
d = 0
for i in range(0, len(aaa)):
  if aaa[i] == "t":
    a = a + 1
  if aaa[i] == "r":
    b = b + 1
  if aaa[i] == "e":
    c = c + 1

while(1):
  a = a - 1
  b = b - 1
  c = c - 2
  if a >= 0 and b >= 0 and c >=0:
    ans = ans + 1
  else:
    break

print ans