using System;
public class Program
{
    public static void Main()
    {
        //int turn = int.Parse(Console.ReadLine() ?? string.Empty);
        //string[] num = (Console.ReadLine() ?? string.Empty).Trim().Split(' ');
        string str = Console.ReadLine() ?? string.Empty;


        int t = 0;
        int r = 0;
        int e = 0;

        for (int i = 0; i < str.Length; i++)
        {
            if(str[i] == 't')
            {
                t++;
            }
            else if (str[i] == 'r')
            {
                r++;
            }
            else if (str[i] == 'e')
            {
                e++;
            }
        }

        if(t >= 1 &&  r >= 1 && e >= 2)
        {
            e /= 2;
            if(t <= r && t <= e)
            {
                Console.WriteLine(t);
            }
            else if(r<=t && r<= e)
            {
                Console.WriteLine(r);
            }
            else
            {
                Console.WriteLine(e);
            }
        }
        else
        {
            Console.WriteLine(0);
        }
    }
}