#define _USE_MATH_DEFINES
#include  <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include <stdlib.h>
#include<stdio.h>
#include <queue>
#include<map>
#include <sstream>
#include<set>
#include<stack>
#include<time.h>
#include <sys/types.h>
#include <tuple>


typedef long long int ll;
//#include<bits/stdc++.h>


using namespace std;



int main()
{

    int Q;
    Q = 1;
    //cin >> Q;
    
    
    while (Q--) {

        string p;
        cin >> p;
        map<char, int>mp;
        for (int i = 0; i < p.size(); i++) {
            mp[p[i]]++;
        }
        cout << min(mp['t'], min(mp['r'], mp['e']/2));


    }
    return 0; 
}