import java.util.Scanner;

public class Test {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		String s = sc.next(), t, r, e;
		int ans = s.length()/4;
		t = s.replaceAll("t", "");
		r = s.replaceAll("r", "");
		e = s.replaceAll("e", "");
		ans = Math.min(ans, s.length()-t.length());
		ans = Math.min(ans, s.length()-r.length());
		ans = Math.min(ans, (s.length()-e.length())/2);
		System.out.println(ans);

		sc.close();
	}
}