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

import static java.lang.System.in;


public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(in));
        String S = reader.readLine();
        int T = 0;
        int R = 0;
        int E = 0;
        for (int i = 0; i < S.length(); i++) {
            char s = S.charAt(i);
            if (s == 't') {
                T += 1;
            } else if (s == 'r') {
                R += 1;
            } else if (s == 'e') {
                E += 1;
            }
        }
        int treeCounter = 0;
        while ((T > 0) && (R > 0) && (E > 1)) {
            T -= 1;
            R -= 1;
            E -= 2;
            treeCounter += 1;
        }
        System.out.println(treeCounter);
    }
}