package jp.co.kokou.sample.no279;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

    public static void main(String[] args) {
        try (InputStreamReader isr = new InputStreamReader(System.in);
             BufferedReader br = new BufferedReader(isr)) {

            String line = br.readLine();
            long tCount = charCount('t', line);
            long rCount = charCount('r', line);
            long eCount = charCount('e', line) / 2;

            long max = Math.min(Math.min(tCount, rCount), eCount);

            System.out.format("%d%n", max);
        } catch (IOException ex) {

        }
    }

    private static long charCount(char c, String seq) {
        return seq.chars().filter(i -> i == (int) c).count();
    }
}