#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++){
      if(s[i] == 't') t++;
      else if(s[i] == 'r') r++;
      else if(s[i] == 'e') e++;
   }
   cout << min({t,r,e / 2}) << endl;
}