#include <iostream>
#include <algorithm>

using namespace std;

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