using System;
using System.Linq;

class Program
{
    static void Main()
    {
        string s = Console.ReadLine();

        int[] tree = new int[3];

        tree[0] = s.Length - s.Replace("t", "").Length;
        tree[1] = s.Length - s.Replace("r", "").Length;
        tree[2] = s.Length - s.Replace("e", "").Length;
        tree[2] /= 2;

        Console.WriteLine(tree.Min());
    }
}