package m.shin;
import java.util.Scanner;
public class Con279 {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		StringBuilder sb = new StringBuilder(s.nextLine());
		s.close();
		int t = 0,r = 0,e = 0;
		for(int i = 0;i < sb.length();i++){
			switch(sb.charAt(i)){
			case 't':t++;
			break;
			case 'r':r++;
			break;
			case 'e':e++;
			break;
			}
		}
		e = e / 2;
		System.out.println(Math.min(t, Math.min(r, e)));


	}

}