import java.util.*;

public class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		String s = sc.next();
		int t = 0;
		int r = 0;
		int e = 0;
		for (int i=0; i<s.length(); i++) {
			if (s.charAt(i)=='t') {t++;}
			else if (s.charAt(i)=='r') {r++;}
			else if (s.charAt(i)=='e') {e++;}
		}
		e /= 2;
		System.out.println(Math.min(t,Math.min(r,e)));
	}
}