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

public class No00000279_Main2 {

	public static void main(String[] args) throws IOException {

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String str = br.readLine();
		int[] cnt = new int[3];
		for(int i = 0; i < str.length(); i++) {
			if(str.charAt(i) == 't') cnt[0] += 1;
			if(str.charAt(i) == 'r') cnt[1] += 1;
			if(str.charAt(i) == 'e') cnt[2] += 1;
		}
		System.out.println(Math.min(cnt[0], Math.min(cnt[1], cnt[2]/2)));
	}
}