#include <bits/stdc++.h>

using namespace std;

#define REP(i, n) for(int i = 0; i < n; i++)

int main() {
    string s;
    cin >> s;

    int cnt[26] = {};
    REP(i, s.length()) cnt[s[i] - 'a']++;

    int ans = min({cnt['t' - 'a'], cnt['r' - 'a'], cnt['e' - 'a'] / 2});
    cout << ans << endl;
    return 0;
}