#include <iostream>
#include <string>

using namespace std;

int hikaku(int num1,int num2)
{
        return (num1 < num2) ? num1 : num2;
}

int count_tree(string str)
{
        int cnt_t = 0;
        int cnt_r = 0;
        int cnt_e = 0;

        for(int i = 0;i <= str.size(); i++){
                if('t' == str[i]) cnt_t++;
                else if('r' == str[i]) cnt_r++;
                else if('e' == str[i]) cnt_e++;
        }

        return hikaku(hikaku(cnt_t,cnt_r),cnt_e/2);
}

int main()
{
        string str;

        cin >> str;

        cout << count_tree(str) << endl;

        return 0;
}