import java.util.*;
import java.lang.*;
import java.io.*;

class Main
{
	public static void main (String[] args) 
	{
		// 入力値の読み込み
		Scanner sc = new Scanner(System.in);
		String str = sc.next();
		int countt = 0;
		int countr = 0;
		int counte = 0;
		
		char t='t';
		char r='r';
		char e='e';
		
		for(char x: str.toCharArray()){
			if(x == t){
				countt++;
			}else if(x == r){
				countr++;
			}else if(x == e){
				counte++;
			}
		}
		
		int min =countt;
		if(countt > countr){
			min = countr;
		}
		if(min > counte/2){
			min = counte;
		}
		
		System.out.println(min);
	}
}