import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String input = sc.nextLine();
		System.out.println(countTrees(input));
	}
	public static int countTrees(final String input) {

		int tQty = 0;
		int rQty = 0;
		int eQty = 0;

		for(int i = 0; i < input.length(); i++) {
			if(input.charAt(i) == 't') {
				tQty++;
			}
			if(input.charAt(i) == 'r') {
				rQty++;
			}
			if(input.charAt(i) == 'e') {
				eQty++;
			}
		}
		eQty /= 2;
		int treeQty = 0;
		while (tQty > 0 && rQty > 0 && eQty > 0) {
			tQty--;
			rQty--;
			eQty--;
			treeQty++;
		}
		return treeQty;
	}
}