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

public class Main {
	public static void main(String[] args)throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		int t = 0;
		int r = 0;
		int e = 0;

		String hoge = br.readLine();
		for(int i=0; i<hoge.length(); i++){
			if(hoge.charAt(i) == 't'){
				t++;
			}else if(hoge.charAt(i) == 'r'){
				r++;
			}else if(hoge.charAt(i) == 'e'){
				e++;
			}
		}

		System.out.println(Math.min(Math.min(t, r), e/2));
	}
}