import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s = sc.next();
		int t = 0, r = 0, 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++;
			}
		}
		System.out.println(Math.min(Math.min(t, r), e / 2));
	}
}