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

namespace No279
{
	class MainClass
	{
		public static void Main (string[] args)
		{
			var line = Console.ReadLine ();
			var tCount = 0;
			var rCount = 0;
			var eCount = 0;
			for (int i = 0; i < line.Length; i++) {
				if (line [i] == 't') {
					tCount++;
				} 
				else if (line [i] == 'r') {
					rCount++;
				}
				else if(line[i] == 'e'){
					eCount++;
				}
			}
			var eUnit = eCount / 2;
			var minValue = Math.Min (tCount, Math.Min (rCount, eUnit));

			Console.WriteLine (minValue.ToString ());
		}
	}
}