import java.util.*;
import java.math.*;
public class Main{
	public static void main(String... args){
		Scanner scan = new Scanner(System.in);
		String s = scan.next();
		System.out.println(Calc(s));
	}

	public static int Calc(String s){
		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++;
			}
		}
		if(t == 0 || r == 0 || e == 0)return 0;
		return (int)Math.min((int)Math.min(t,r),e/2);
	}
}