#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
int a[3];

int main() {
  string s;
  int ans = 1000000;
  cin >> s;
  for (auto& e : s) {
    if (e == 't') a[0]++;
    else if (e == 'r') a[1]++;
    else if (e == 'e') a[2]++;
  }
  a[2] /= 2;
  for (auto& e : a) {
    ans = min(ans, e);
  }
  cout << ans << endl;
}