#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll = long long;
using mint = atcoder::modint998244353;
using maxt = atcoder::modint1000000007;

int main() {
  string S;
  cin >> S;
  int t_cnt = 0, r_cnt = 0, e_cnt = 0;
  for(char o : S) {
    if(o == 't') {
      t_cnt++;
    }
    else if(o == 'r') {
      r_cnt++;
    }
    else if(o == 'e') {
      e_cnt++;
    }
  }
  cout << min(t_cnt, min(r_cnt, e_cnt / 2)) << endl;
}