// No.279 木の数え上げ
package main

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

func main() {
	var s string
	reader := bufio.NewReader(os.Stdin)
	fmt.Fscan(reader, &s)

	t, r, e := strings.Count(s, "t"), strings.Count(s, "r"), (strings.Count(s, "e") / 2)
	fmt.Println(min(t, r, e))
}