package main

import . "fmt"

func main() {
	var s string
	Scan(&s)
	m:=map[rune]int{}
	for _,c:=range s {
		m[c]++
	}
	t:=m['t']
	r:=m['r']
	e:=m['e']/2
	if r<t {
		t=r
	}
	if e<t {
		t=e
	}
	Println(t)
}