package yuki_coder;

import java.util.Scanner;

public class No_279 {
public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);
	String S = sc.nextLine();
	sc.close();
	String str;
	int t = 0;
	int r = 0;
	int e = 0;
	int tree = 0;
	int memory = 0;
	for(int i = 1; i <= S.length(); i++){
		str = S.substring(i-1,i);
		if(str.equals("t")){
			t++;
		}
		if(str.equals("r")){
			r++;
		}
		if(str.equals("e")){
			e++;
		}
	}
	memory = t;
	if(memory > r){
		memory = r;
	}
	if(memory > e/2){
		memory = e/2;
	}
	tree = memory;
	System.out.println(tree);
}
}