#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++){
        switch (s[i]) {
            case 't' : t++; break;
            case 'r' : r++; break;
            case 'e' : e++; break;
            default : continue;
        }
    }

    cout << min(min(t, r), e/2) << endl;

    return 0;
}