using System;
using System.Linq;

public class P0279 {
    public static void Main() {
        var t = 0;
        var r = 0;
        var e = 0;
        foreach(char c in Console.ReadLine().Trim().ToCharArray()) {
            if (c == 't') t++;
            if (c == 'r') r++;
            if (c == 'e') e++;
        }
        Console.WriteLine(Math.Min(Math.Min(t, r), e / 2));
    }
}