#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <sstream>
#include <complex>
#include <algorithm>
#include <functional>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <cmath>
#include <cassert>
#include <fstream>
#define REP(i,n) for(int i=0;i<n;i++)
#define FOR(a,b) for(:a<b;a++)
#define SSTR( x ) static_cast< std::ostringstream & >( \
        ( std::ostringstream() << std::dec << x ) ).str()
#define ALL(s) (s).begin(), (s).end()
using namespace std;
typedef long long unsigned int llu;
typedef long long ll;

int main (){
  string s;
  while (cin >> s){
    int t = 0;
    int r = 0;
    int e = 0;
    REP(i,s.size()){
      if(s[i] == 't'){
	t++;
      }else if(s[i] == 'r'){
	r++;
      }else if(s[i] == 'e'){
	e++;
      }
    }
    int ans = 0;
    ans = min(t,r);
    ans = min(ans,e/2);
    
    cout << ans << endl;
  }
  return 0;
}