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++;
            }
            if(c ==  'r')
            {
                r++;
            }
            if(c == 'e')
            {
                e++;
            }
        }
        str = "";
        int count = 0;
        while (t > 0 && r > 0 && e >= 2)
        {
            if(t >= 1 && r >= 1 && e >= 2)
            {
                count++;
                t--;
                r--;
                e-=2;
            }
        }
        Console.WriteLine(count);
    }
}