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

class Main279 {
	
	public static void main (String[] args) throws IOException {
		BufferedReader br = 
			new BufferedReader(new InputStreamReader(System.in));
		
		String s = br.readLine();
		int cntT = 0, cntR = 0, cntE = 0;
		
		for (int i = 0; i < s.length(); i++) {
			char c = s.charAt(i);
			if (c == 't') cntT++;
			if (c == 'r') cntR++;
			if (c == 'e') cntE++;
		}
		
		System.out.println(Math.min(Math.min(cntT, cntR), cntE / 2));
	}
}