using System;
using System.Linq;  // 追加

public class Program {
	public void Solve() {
		Char[] c = Console.ReadLine().ToCharArray();
		int t = c.Count(x=>x.Equals('t'));
		int r = c.Count(x=>x.Equals('r'));
		int e = c.Count(x=>x.Equals('e'));
		int count = 0;
		while (true) {
			t -= 1;
			r -= 1;
			e -= 2;
			if (t < 0 || r < 0 || e < 0) {
				break;
			}
			count++;
		}
		Console.WriteLine(count);
	}
	
	public static void Main(string[] args) {
		Program program = new Program();
		program.Solve();
	}
}