//Normal

#define _GLIBCXX_DEBUG
#define ll long long
#include <bits/stdc++.h>
using namespace std;
using Graph = vector<vector<int>>;

void print(auto a){
  cout << a;
}

void prints(auto a){
  cout << a << " ";
}

void prints(){
  cout << " ";
}

void printl(auto a){
  cout << a << endl;
}

void printl(){
  cout << endl;
}

void fix(int n){
  cout << fixed << setprecision(n);
}

int siz(string s){
  return (int)s.size();
}

int main(){
  string S; cin >> S;
  map<char, int> mp;
  
  for(int i = 0; i < siz(S); i++){
    mp[S[i]]++;
  }
  
  int ans = 1e9;
  for(auto p: mp){
    char C = p.first;
    
    if(C != 't' and C != 'r' and C != 'e') continue;
    
    C == 'e' ? ans = min(ans, p.second/2) : ans = min(ans, p.second);
  }
  printl(ans);
  
  return 0;
}