#include <bits/stdc++.h>
using namespace std;

int main() {
  string s;
  cin >> s;
  int tree[3] = {0,0,0};
  for (int i = 0; i < s.size(); i++) {
    if (s[i] == 't') tree[0]++;
    else if (s[i] == 'r') tree[1]++;
    else if (s[i] == 'e') tree[2]++; 
  }
  tree[2] /= 2;
  sort(tree, tree + 3);
  cout << tree[0] << endl;
  return 0;
}