#include <bits/stdc++.h>

#define REP(i, n) for (int i = 0; i< (n); i++)

using namespace std;

int main() {
  string S;
  cin >> S;
  int t = 0;
  int r = 0;
  int e = 0;
  REP(i, (int)S.size()) {
    char c = S[i];
    if (c == 't') t++;
    else if (c == 'r') r++;
    else if (c == 'e') e++;
  }
  cout << min(min(t, r), e/2) << endl;
  return 0;
}