import java.util.*;

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