import java.util.Scanner;

public class No279 {

    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        String str = s.next();
        int t = 0;
        int r = 0;
        int e = 0;
        for (int i = 0; i < str.length(); i++) {
            switch (str.charAt(i)) {
                case 't':
                    t++;
                    break;
                case 'r':
                    r++;
                    break;
                case 'e':
                    e++;
                    break;
            }
        }
        System.out.println(Math.min(Math.min(t, r), e / 2));
    }
}