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

class Magatro
{
    static void Main()
    {
        string S = Console.ReadLine();
        int[] tree = new int[3];
       
   for(int i = 0; i < S.Length; i++)
        {
            switch (S[i])
            {
                case 't':
                    tree[0]++;
                    break;
                case 'r':
                    tree[1]++;
                    break;
                case 'e':
                    tree[2]++;
                    break;
            }
        }
        tree[2] /= 2;
        Console.WriteLine(tree.Min());
    }
}