import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        codeabbey solver = new codeabbey();
        solver.solve(1, in, out);
        out.close();
    }

    static class codeabbey {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int t = 0, r = 0, e = 0;
            String str = in.nextLine(); // 10^6

            for (char ch : str.toCharArray()) {
                if (ch == 't') t++;
                if (ch == 'r') r++;
                if (ch == 'e') e++;
            }
//        System.out.println("t:" + t + " ,r:" + r + " ,e:" + e);
            e = e / 2;
            int ans = Math.min(t, r);
            ans = Math.min(ans, e);
            out.println(ans);
        }

    }
}