package main

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

func main() {
    s := Input()
    t := strings.Count(s, "t")
    r := strings.Count(s, "r")
    e := strings.Count(s, "e")/2
    if r < t { t = r }
    if e < t { t = e }
    fmt.Println(t)
}

var sc = bufio.NewScanner(os.Stdin)
func Input() string {
    sc.Scan()
    return sc.Text()
}