import java.util.Scanner;
import java.util.Arrays;

public class Exercise55{
  public static void main (String[] args){

    Scanner sc = new Scanner(System.in);

    String str = sc.next();

    String[] strArray = str.split("");

    int tCount = 0;
    int rCount = 0;
    int eeCount = 0;

    for(int i = 0; i < strArray.length; i++){
      if (strArray[i].equals("t")){
        tCount++;
      }else if (strArray[i].equals("r")){
        rCount++;
      }else if (strArray[i].equals("e")){
        eeCount++;
      }
    }
    eeCount /= 2;
    int min = Math.min(tCount, Math.min(rCount, eeCount));
    System.out.println(min);
  }
}