#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    string s;
    cin >> s;
    vector<int> tree(3);
    for(int i = 0;i < s.length();i++){
        if(s[i] == 't')tree[0]++;
        else if(s[i] == 'r')tree[1]++;
        else if(s[i] == 'e')tree[2]++;
    }
    tree[2]/=2;
    sort(tree.begin(),tree.end());
    cout << tree[0] << endl;
    return 0;
}