#include <iostream>
#include <math.h>
#include <algorithm>
#include <functional>
#include <vector>
#include <typeinfo>
#include <climits>
#include <ctype.h>
#include <string>
using namespace std;
#define INIT cin.tie(0); ios::sync_with_stdio(false);
#define FOR(i, a, n) for (int i = a; i < n; i++)
#define REP(i, n) for(int i = 0; i < n; i++)

int main()
{
    INIT;

    string s;
    cin >> s;

    int A[3] = {};
    REP(i, s.size()){
        if(s[i] == 't') A[0]++;
        else if(s[i] == 'r') A[1]++;
        else if(s[i] == 'e') A[2]++;
    }
    int cnt = 0;
    while(1){
        A[0]--;
        A[1]--;
        A[2] -= 2;
        if(A[0] < 0 or A[1] < 0 or A[2] < 0) break;
        else cnt += 1;
    }
    cout << cnt << endl;

    return 0;
}