#include "iostream"
using namespace std;

int main(){
    string str;
    int ct,cr,ce;
    ct = cr = ce = 0;
    cin >> str;
    for (auto c : str){
        if (c == 't')
            ct++;
        else if (c == 'r')
            cr++;
        else if (c == 'e')
            ce++;
    }
    cout << min(min(ct,cr),ce/2) << endl;
    return 0;
}