import java.util.Scanner;

public class Main{
	public static void main(String args[]){
		Scanner sc=new Scanner(System.in);
		while(sc.hasNext()){
			char[] a=new char['z'-'a'+1];
			String str=sc.next();
			for(int i=0;i<str.length();i++) a[str.charAt(i)-'a']++;
			int res=Math.min(Math.min(a['t'-'a'],a['r'-'a']), a['e'-'a']/2);
			System.out.println(res);
		}
	}
}