import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main{
	public static void main(String[] args){
		try {
			(new Solve()).solve();
		} catch (NumberFormatException | IOException e) {
			e.printStackTrace();
		}
	}
}

class Solve{
	void solve() throws NumberFormatException, IOException{
		final ContestScanner in = new ContestScanner();
		char[] s = in.nextToken().toCharArray();
		int[] alp = new int[26];
		for(int i=0; i<s.length; i++){
			alp[s[i]-'a']++;
		}
		System.out.println(Math.min(alp['r'-'a'], Math.min(alp['t'-'a'], alp['e'-'a']/2)));
	}
}

class ContestScanner {
	private BufferedReader reader;
	private String[] line;
	private int idx;

	public ContestScanner() throws FileNotFoundException {
		reader = new BufferedReader(new InputStreamReader(System.in));
	}

	public ContestScanner(String filename) throws FileNotFoundException {
		reader = new BufferedReader(new InputStreamReader(new FileInputStream(
				filename)));
	}

	public String nextToken() throws IOException {
		if (line == null || line.length <= idx) {
			line = reader.readLine().trim().split(" ");
			idx = 0;
		}
		return line[idx++];
	}

	public long nextLong() throws IOException, NumberFormatException {
		return Long.parseLong(nextToken());
	}

	public int nextInt() throws NumberFormatException, IOException {
		return (int) nextLong();
	}

	public double nextDouble() throws NumberFormatException, IOException {
		return Double.parseDouble(nextToken());
	}
}