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

class Program
{
    public void Solve()
    {
        string S = Console.ReadLine();

        int[] cnt = new int[3];
        cnt[0] = S.Count(x => x == 't');
        cnt[1] = S.Count(x => x == 'r');
        cnt[2] = S.Count(x => x == 'e') / 2;

        Array.Sort(cnt);

        Console.WriteLine(cnt[0]);
    }

    static void Main()
    {
        var solver = new Program();
        solver.Solve();
    }
}