//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;
  int t = 0, r = 0, e = 0;
  
  for(int i = 0; i < siz(S); i++){
    if(S[i] == 't') t++;
    if(S[i] == 'r') r++;
    if(S[i] == 'e') e++;
  }
  
  printl(min({t, r, e/2}));
  
  return 0;
}