#include<iostream>
#include<string>
#include<algorithm>
using namespace std;

int main(){
  string s;
  int t=0,r=0,e=0;
  cin >> s;
  for(int i=0;i<s.size();i++){
    switch (s[i]){
      case 't':
        t++;
        break;
      case 'r':
        r++;
        break;
      case 'e':
        e++;
        break;
      default:
        break;
    }
  }
  e/=2;
  cout << min({t,r,e}) << "\n";
  return 0;
}