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

class yc
{
    public static void Main()
    {
        string str = Console.ReadLine();
        List<char> listStr = new List<char>();
        int[] trees = new int[3];
        int key;

        for (int i = 0; i < str.Length; i++)
        {
            listStr.Add(str[i]);
        }

        for (int i = 0; i < str.Length; i++)
        {
            key = listStr.IndexOf('t');
            if (key != -1)
            {
                trees[0]++;
                listStr.Remove(listStr[key]);
            }
            key = listStr.IndexOf('r');
            if (key != -1)
            {
                trees[1]++;
                listStr.Remove(listStr[key]);
            }
            key = listStr.IndexOf('e');
            if (key != -1)
            {
                trees[2]++;
                listStr.Remove(listStr[key]);
            }
        }
        trees[2] /= 2;

        Console.WriteLine(trees.Min());

    }
}