using System.Linq;
using System;

public class Hello
{
    public static void Main()
    {
        var m = new int[3];
        var s = Console.ReadLine().Trim();
        foreach (var x in s)
            if (x == 't') m[0]++;
            else if (x == 'r') m[1]++;
            else if (x == 'e') m[2]++;
        m[2] /= 2;
        Console.WriteLine(m.Min());
    }
}