package main

import "fmt"

func main() {
	var S string
	fmt.Scan(&S)
	set := make(map[byte]int, 0)
	for i := 0; i < len(S); i++ {
		if S[i] == 't' || S[i] == 'r' || S[i] == 'e' {
			set[S[i]]++
		}
	}
	fmt.Println(min(set['t'], min(set['r'], set['e']/2)))
}
func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}