#include <iostream>

int main(void){
  int it=0;
  int ir=0;
  int ie=0;
  int x=0;
  std::string a;
  std::cin >> a;
  const char* ca = a.c_str();
  for(int i=0;i<a.length();i++){
    if(ca[i]=='t') it++;
    if(ca[i]=='r') ir++;
    if(ca[i]=='e') ie++;
  }
  //std::cout << it << " " << ir << " " << ie <<std::endl;
  if(it<=ie/2){
    if(ir>=it) x=it;
    else x=ir;
  }
  else x=ie/2;
  std::cout << x << std::endl;
}