using System;
public class Program
{
    public static void Main()
    {
        //int num = 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;
        foreach (char c in str)
        {
            if(c == 't')
            {
                t++;
                continue;
            }
            if(c ==  'r')
            {
                r++;
                continue;
            }
            if(c == 'e')
            {
                e++;
                continue;
            }
        }

        if(t >= 1 && r >= 1 && e >= 2)
        {
            int ee = e / 2;

            if(t > r)
            {
                if(r > ee)
                {
                    Console.WriteLine(ee);
                    
                }
                else
                {
                    Console.WriteLine(r);
                }
            }
            else
            {
                if(t > ee)
                {
                    Console.WriteLine(ee);
                }
                else
                {
                    Console.WriteLine(t);
                }
            }
        }
    }
}