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

int main(){

  string s;
  int a[3] = {};

  cin >> s;
  for(int i=0;i<s.size();i++){
    if(s[i] == 't') a[0]++;
    if(s[i] == 'r') a[1]++;
    if(s[i] == 'e') a[2]++;
  }

  a[2] /= 2;

  cout << min(a[0], min(a[1], a[2])) << endl;

}