package main

import (
	"bufio"
	"fmt"
	"os"
	"strings"
)

func main() {
	rdr := bufio.NewReaderSize(os.Stdin, 1000001)
	l, _, _ := rdr.ReadLine()
	str := string(l)
	var min = 1000001
	t := strings.Count(str, "t")
	r := strings.Count(str, "r")
	e := strings.Count(str, "e") / 2
	if min > t {
		min = t
	}
	if min > r {
		min = r
	}
	if min > e {
		min = e
	}
	fmt.Println(min)
}