package main

import (
	"fmt"
)

func main() {
	solve279()
}

func solve279(){
	var S string
	fmt.Scan(&S)
	var t, r, e int
	for i:=0; i<len(S); i++ {
	    if string(S[i])=="t"{
			t++
		}else if string(S[i])=="r"{
			r++
		}else if string(S[i])=="e"{
			e++
		}
	}
	fmt.Println(min(min(t, r), e/2))
}

func min(a, b int) int {
	if a < b {
		a, b = b, a
	}
	return b
}