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

int main() {
    string S;
    cin >> S;
    int t = 0, r = 0, 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++; } 
    }
    int ans;
    ans = min(t, min(r, e / 2));
    cout << ans << endl;
    return 0;
}