import java.util.*;

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

		String S = sc.next();
		
		char[] charS = S.toCharArray();
		
		int[] flag = new int[]{0, 0, 0};
		
		for(int i = 0; i < charS.length; i++) {
			if(charS[i] == 't') {
				flag[0]+=2;
			} else if(charS[i] == 'r') {
				flag[1]+=2;
			} else if(charS[i] == 'e') {
				flag[2]++;
			}
		}
		
		int min = Integer.MAX_VALUE;;
		
		for(int i = 0; i < 3; i++) {
			if(flag[i] < min) {
				min = flag[i];
			}
		}
		
		System.out.println(min / 2);
	}
}