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

namespace Yuki
{
    class Program
    {
        static void Main(string[] args)
        {
            string S = Console.ReadLine();

            int[] a = { 0, 0, 0 };

            for (int i = 0; i < S.Length; i++)
            {
                if (S[i].Equals('t')) a[0]++;
                if (S[i].Equals('r')) a[1]++;
                if (S[i].Equals('e')) a[2]++;
            }

            a[2] = a[2] / 2;
            Console.WriteLine(a.Min());
        }
    }
}