package yukicoder;

import java.util.Scanner;

public class Yuki279 {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);
		String str = scan.next();
		scan.close();

		// String strArr[] = str.split("");

		int t = 0;
		int r = 0;
		int e = 0;
		int count = 0;

		// for(int i = 0; i < strArr.length; i++ ) {
		for (int i = 0; i < str.length(); i++) {
			switch (str.charAt(i)) {
			case 't':
				t += 1;
				break;
			case 'r':
				r += 1;
				break;
			case 'e':
				e += 1;
				break;
			}
		}

		while (t >= 1 && r >= 1 && e >= 2) {
			if (t >= 1 && r >= 1 && e >= 2) {
				count++;
				t--;
				r--;
				e -= 2;
			} else {
				break;
			}
		}
		System.out.println(count);
	}
}