using LIB;
using System;
using System.Linq;
using System.Text;
using System.Collections.Generic;

class Program
{
    static void Main(string[] args)
    {
        string s = IO.R<string>();
        int tc = s.Count(c => c == 't');
        int rc = s.Count(c => c == 'r');
        int ec = s.Count(c => c == 'e') / 2;
        IO.W(Math.Min(Math.Min(tc, rc), ec));
        IO.WFLUSH();
    }
}

namespace LIB
{
    public class IO
    {
        private const int WMAX = 1000;
        private static StringBuilder S = new StringBuilder();
        public static T R<T>() { return UTIL.PARSE<T>(R()); }
        public static T[] R<T>(char s = ' ') { return R().Split(s).Select(UTIL.PARSE<T>).ToArray(); }
        public static T[] R<T>(int l) { T[] r = new T[l]; for (int i = 0; i < l; i++) { r[i] = R<T>(); } return r; }
        public static T[][] R<T>(int l, char s = ' ') { T[][] r = new T[l][]; for (int i = 0; i < l; i++) { r[i] = R<T>(s); } return r; }
        private static string R() { return Console.ReadLine(); }
        public static void W(object v, bool lf = true) { S.Append(UTIL.PARSE<string>(v)); if (lf == true) { S.Append('\n'); } if (S.Length >= WMAX) { WFLUSH(); } }
        public static void WFLUSH() { Console.Write(S.ToString()); S.Clear(); }
    }
    public class UTIL
    {
        public static T PARSE<T>(object value) { return (T)(Convert.ChangeType(value, typeof(T))); }
    }
    public class MEMO<Key, Result>
    {
        private Dictionary<Key, Result> R;
        public MEMO() { R = new Dictionary<Key, Result>(); }
        public Result EXEC(Key k, Func<Key, Result> f) { Result r; if (R.ContainsKey(k)) { r = R[k]; } else { r = f(k); R.Add(k, r); } return r; }
    }
}