#include <bits/stdc++.h>

using namespace std;

#define debug(x) cerr << #x << " -> " << x << "\n"

static const int INF = 1e9 + 7;
static const double EPS = 1e-10;
static const int dx[] = {0, 1, 0, -1, 1, 1, -1, -1};
static const int dy[] = {1, 0, -1, 0, 1, -1, 1, -1};

template<class T> ostream &operator<<(ostream &os, vector<T> &v){
  for(int i = 0; i < v.size(); i++){
    if(i) os << " ";
    os << v[i];
  }
  return os;
}

int main(){
  ios::sync_with_stdio(false);
  cin.tie(0);
  string str;
  cin >> str;
  sort(str.begin(), str.end());
  string tre = "tre";
  int ans = INF;
  for(int i = 0; i < 3; i++){
    ans = min<int>(ans, (upper_bound(str.begin(), str.end(), tre[i]) - lower_bound(str.begin(), str.end(), tre[i])) / (1 + (i == 2)));
  }
  cout << ans << "\n";
  return 0;
}