#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); ++i)

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