import math._

object Main {
  def main(args: Array[String]) {
    val sc = new java.util.Scanner(System.in)
    val s = sc.next

    val t = s count (_ == 't')
    val r = s count (_ == 'r')
    val e = s count (_ == 'e')
    println(min(t, min(r, e/2)))
  }
}