import java.util.*;
import java.util.Map.Entry;
import java.math.*;
import java.awt.geom.*;
import java.io.*;
      
      
public class Main {	

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		char[] S = sc.next().toCharArray();
		int T = 0;
		int R = 0;
		int E = 0;
		for(int i = 0; i < S.length; i++) {
			if(S[i] == 't') T++;
			if(S[i] == 'r') R++;
			if(S[i] == 'e') E++;
		}
		System.out.println(Math.min(Math.min(T, R), E/2));
	}
}