using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static string InputPattern = "Input4";

    static List<string> GetInputList()
    {
        var WillReturn = new List<string>();

        if (InputPattern == "Input1") {
            WillReturn.Add("takahashikunlovesyukicoder");
            //1
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("treapisnotki");
            //0
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("eerteerteerteert");
            //4
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static void Main()
    {
        List<string> InputList = GetInputList();
        string S = InputList[0];
        int CntT = S.Count(X => X == 't');
        int CntR = S.Count(X => X == 'r');
        int CntE = S.Count(X => X == 'e');

        int Answer = Math.Min(CntT, CntR);
        Answer = Math.Min(Answer, CntE/2);
        Console.WriteLine(Answer);
    }
}