import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String S = sc.next();
        int t = 0;
        int r = 0;
        int e = 0;
        for(int i=0; i<S.length(); i++){
            if( 't'==S.charAt(i) ){
                t++;
            }else if( 'r'==S.charAt(i) ){
                r++;
            }else if( 'e'==S.charAt(i) ){
                e++;
            }
        }
        int min = Math.min(t, Math.min(r,e/2) );
        System.out.println(min);
    }
}