#include <iostream>
#include <cstdlib>
#include <string>
#include <vector>

int main()
{
    std::string s;
    int t, r, e;
    int min;
    t=0;r=0;e=0;
    std::cin >> s;
    for(auto i = s.begin(); i != s.end(); i++){
        switch(*i){
            case 't':
                t++;
                break;
            case 'r':
                r++;
                break;
            case 'e':
                e++;
                break;
            default:
                break;
        }
    }
    if(e % 2 == 1) e--;
    e /= 2;
    min = t;
    if(r < min){
        min = r;
    }
    if(e < min){
        min = e;
    }
    std::cout << min << std::endl;
}