package main

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

func main() {
	S := nextLine()
	t := 0
	r := 0
	e := 0
	for _, v := range S {
		switch v{
		case 't': {
			t+=1
		}
		case 'r': {
			r+=1
		}
		case 'e': {
			e+=1
		}

		}

	}
	PrintI(minA(t, r, e/2))
}

var s = bufio.NewScanner(os.Stdin)

func next() string {
	s.Split(bufio.ScanWords)
	s.Scan()
	return s.Text()
}
func nextLine() string {
	s.Split(bufio.ScanLines)
	s.Scan()
	return s.Text()
}

func nextInt() int {
	i, e := strconv.Atoi(next())
	if e != nil {
		panic(e)
	}
	return i
}
func nextLong() int64 {
	i, e := strconv.ParseInt(next(), 10, 64)
	if e != nil {
		panic(e)
	}
	return i
}
func min(a int, b int) int {
	if a < b {
		return a
	}
	return b
}

func minA(arg ...int) int {
	var s = arg[0]
	for _, v := range arg {
		s = min(s, v)
	}
	return s
}
func PrintI(args ...int) {
	fmt.Println(strings.Join(mapToString(args), " "))
}

func mapToString(arr []int) []string {
	ret := make([]string, len(arr))
	for i := 0; i < len(arr); i++ {
		ret[i] = strconv.Itoa(arr[i])
	}
	return ret
}