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();

    char[] strArray = str.toCharArray();

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

    for(int i = 0; i < strArray.length; i++){
      if (strArray[i] == 't'){
        tCount++;
      }else if (strArray[i] == 'r'){
        rCount++;
      }else if (strArray[i] == 'e'){
        eeCount++;
      }
    }
    eeCount /= 2;
    int min = Math.min(tCount, Math.min(rCount, eeCount));
    System.out.println(min);
  }
}