import java.util.Scanner;
public class Main{
	private static Scanner sc=new Scanner(System.in);
	public static void main(String args[])throws Exception{
		int t=0,r=0,e=0;
		char are[]=sc.nextLine().toCharArray();
		for(char element:are){
			switch(element){
			case't':t++;break;
			case'r':r++;break;
			case'e':e++;break;
			}
		}
		int min=Math.min(Math.min(t,r),e/2);
		System.out.println(min);
	}
}