import java.util.*;

public class Run {
    public static void main (String arg[]) {
        Scanner scan = new Scanner(System.in);
        int ans;
        String N = scan.next();
        String tmp;
        int t = 0, r = 0, e = 0;
        for (int i = 0; i < N.length(); i++) {
            tmp = N.substring(i, i+1);
            if (tmp.equals("t")) t++;
            else if (tmp.equals("r")) r++;
            else if (tmp.equals("e")) e++;
        }

        ans = Math.min(Math.min(t, r), e/2);
        System.out.println(ans);
    }
}