import java.util.Arrays;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.Set;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int t_count = 0, r_count = 0, e_count = 0;
		for(final char c : sc.next().toCharArray()){
			switch(c){
			case 't': t_count++; break;
			case 'r': r_count++; break;
			case 'e': e_count++; break;			
			}
		}
		
		
		System.out.println(Math.min(e_count / 2, Math.min(t_count, r_count)));
		
	}

}