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

int ans,t,r,e;

int main(){
   string s;
   cin >> s;
   for(int i = s.size();i--;){
      if(s[i] == 't') t++;
      else if(s[i] == 'r') r++;
      else if(s[i] == 'e') e++;
   }
   ans = min({t,r,e /2});
   cout << ans << endl;
}