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


namespace yukicoder
{
    class Program
    {

        static void Main(string[] args)
        {

            string S = Console.ReadLine();
            string[] str = new string[S.Length];

            int Tcount = 0 , Rcount = 0 , Ecount = 0 , treecount = 0;

            for(int i = 0; i < S.Length; i++)
            {
                str[i] = S.Substring(i, 1);
                if (str[i] == "t")
                {
                    Tcount++;
                }
                else if (str[i] == "r")
                {
                    Rcount++;
                }
                else if (str[i] == "e")
                {
                    Ecount++;
                }
            }
            
            
            while (Tcount >= 1 && Rcount >= 1 && Ecount >= 2)
            {

                Tcount = Tcount - 1;
                Rcount = Rcount - 1;
                Ecount = Ecount - 2;
                treecount++;
            }
            Console.WriteLine(treecount);
        }
    }
}