using System;
using System.Collections.Generic;
using System.Linq;
using System.Numerics;
static public class Program
{
    static public void Main()
    {
        var s = Console.ReadLine();
        s.ToCharArray().ValidateArray(x => 'a' <= x && x <= 'z');
        readEOF();
        var t = 0;
        var r = 0;
        var e = 0;
        foreach (var x in s)
        {
            if (x == 't') t++;
            else if (x == 'r') r++;
            else if (x == 'e') e++;
        }
        var ans = new int[] { t, r, e / 2 };
        Console.WriteLine(ans.Min());
    }
    static public void Swap<T>(ref T a, ref T b) { var tmp = a; a = b; b = tmp; }
    static void readEOF()
    {
        if (Console.In.Peek() >= 0)
            throw new Exception("invalid input too long input file");
    }

}
static public class Ex
{
    static public T Validate<T>(this T input, Func<T, bool> f)
    {
        if (!f(input))
            throw new Exception("invalid input");
        return input;
    }
    static public T[] ValidateArray<T>(this T[] input, Func<T, bool> f)
    {
        foreach (var x in input)
            if (!f(x))
                throw new Exception("invalid input");
        return input;
    }
}