public class Main{
  public static void main(String[] args){
    String line = new java.util.Scanner(System.in).next();
    int tcou = 0, rcou = 0, ecou = 0, cou = 0;
    for(int i=0;i<line.length();i++){
      if(line.charAt(i) == 't')tcou++;
      if(line.charAt(i) == 'r')rcou++;
      if(line.charAt(i) == 'e')ecou++;
    }
    while(tcou > 0 && rcou > 0 && ecou > 1){
      cou++;
      tcou--;
      rcou--;
      ecou-=2;
    }
    System.out.println(cou);
  }
}