package me.yukicoder;

import java.util.Scanner;

/**
 * http://yukicoder.me/problems/531
 * star1
 */
public class YukiCoder279 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String s = sc.next();

        int t = 0, r = 0, e = 0;
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            if (c == 't') {
                t++;
            } else if (c == 'r') {
                r++;
            } else if (c == 'e') {
                e++;
            }
        }
        int num = Math.min(Math.min(t, r), e / 2);
        System.out.println(num);
    }
}
/*

takahashikunlovesyukicoder
1

treapisnotki
0

eerteerteerteert
4
*/