import java.util.Scanner;
public class Main {
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		String str=sc.next();
		int countT=0;
		int countR=0;
		int countE=0;
		for(int i=0;i<str.length();i++){
			if(str.charAt(i)=='t')
				countT++;
			if(str.charAt(i)=='r')
				countR++;
			if(str.charAt(i)=='e')
				countE++;
		}
		countE=countE/2;
		int count=Math.min(countT, Math.min(countR, countE));
		System.out.println(count);
	}
}