import java.util.Scanner;


public class Main_yukicoder279 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        char[] s = sc.next().toCharArray();
        int[] cnt = new int[3];

        for (int i = 0; i < s.length; i++) {
        	if (s[i] == 't') {
        		cnt[0]++;
        	} else if (s[i] == 'r') {
        		cnt[1]++;
        	} else if (s[i] == 'e') {
        		cnt[2]++;
        	}
        }

        int ret = cnt[0];
        ret = Math.min(ret, cnt[1]);
        ret = Math.min(ret, cnt[2] / 2);
        
        System.out.println(ret);

        sc.close();
    }
}