#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long ul;
typedef signed long long ll;
ul over = 1000000007;

int main(void)
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed;
  string s;
  cin >> s;
  ll t=0, r=0, e=0;
  for (auto c : s) {
    if (c=='t') t++;
    if (c=='r') r++;
    if (c=='e') e++;
  }
  cout << min(t, min(r, e/2)) << endl;
  return 0;
}