#include <algorithm>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>
using namespace std;
typedef pair<int, int> pii;
typedef vector<int> vi;
#define rep(i,x) for(int i=0;i<(int)(x);++i)

int main(){
    int ret, t = 0, r = 0, e = 0;
    string str;
    cin >> str;

    rep(i, str.size()) {
        if (str[i] == 't') ++t;
        else if (str[i] == 'r') ++r;
        else if (str[i] == 'e') ++e;
    }
    
    ret = (t >= r) ? r : t;
    ret = (ret >= e/2) ? e/2 : ret;
    cout << ret << endl;
    return 0;
}