#include <iostream>
#include <list>
#include <vector>
#include <string>
#include <stdio.h>
#include <stdint.h>
using namespace std;

using uint = unsigned int;
using ll = long long;

#define CIN( LL , A ) LL A; cin >> A 
#define GETLINE( A ) string A; getline( cin , A ) 


int main()
{

  CIN( string , S );
  const uint& size = S.size();
  const string t = "t";
  const string r = "r";
  const string e = "e";
  ll t_num = 0;
  ll r_num = 0;
  ll e_num = 0;

  for( ll i = 0 ; i < size ; i++ ){

    const string c = S.substr( i , 1 );

    if( c == t ){

      t_num++;

    } else if( c == r ){

      r_num++;

    } else if( c == e ){

      e_num++;

    }

  }

  ll min_num = t_num;

  if( r_num < min_num ){

    min_num = r_num;

  }

  e_num /= 2;

  if( e_num < min_num ){

    min_num = e_num;

  }

  cout << min_num << endl;
  return 0;

}