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

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

    int count[3] = {};
    for(int i = 0; i < s.length(); i++){
        if(s[i] == 't')
            count[0]++;
        else if(s[i] == 'r')
            count[1]++;
        else if(s[i] == 'e')
            count[2]++;
    }

    cout << min({count[0],count[1],count[2]/2}) << endl;

    return 0;
}