import java.util.Scanner;
import java.lang.Math;
import java.lang.StringBuilder;
import java.util.regex.Pattern;
import java.util.Arrays;


    public class Main {
        public static void main(String[] args) {
            Scanner sc = new Scanner(System.in);
  
            String s = sc.nextLine();
            StringBuilder sb = new StringBuilder(s);
            int countT = 0;
            int countR = 0;
            int countE = 0;

            for(int i=0; i<s.length(); i++){
                switch(sb.charAt(i)){
                    case 't':
                        countT++;
                        break;
                    case 'r':
                        countR++;
                        break;
                    case 'e':
                        countE++;
                        break;
                }
            }
            
            
            
            System.out.println(min(countT,countR,countE/2));
        }
        
        public static int min(int a, int b, int c){
        	int minVal=a;
        	if(b<minVal) minVal = b;
        	if(c<minVal) minVal = c;
        	return	minVal;
        }
        
    }