using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace template
{
    class Program
    {
        static void Main(string[] args)
        {
            string s = Console.ReadLine();
            int[] ret = new int[3];
            for (int i = 0; i < s.Length; i++)
            {
                switch (s[i])
                {
                    case ('t'):
                        {
                            ret[0]++;
                            break;
                        }
                    case ('r'):
                        {
                            ret[1]++;
                            break;
                        }
                    case ('e'):
                        {
                            ret[2]++;
                            break;
                        }
                }
            }
            ret[2] /= 2;
            Console.WriteLine(ret.Min());
        }
    }
}