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

int main() {
  vector<int> TRE(3);
  string S; cin >> S;
  for(int i = 0; i < (int)S.size(); i++){
    if(S[i] == 't') TRE[0]++;
    if(S[i] == 'r') TRE[1]++;
    if(S[i] == 'e') TRE[2]++;
  }
  cout << min(TRE[0], min(TRE[1], TRE[2]/2)) << endl;
}