#include <bits/stdc++.h>
using namespace std;
int main(){
    string s;
    cin >> s;
    int tre[3] ={0,0,0};
    for(int i=0; i < s.size(); i++){
        if(s[i] == 't') tre[0]++;
        if(s[i] == 'r') tre[1]++;
        if(s[i] == 'e') tre[2]++;
    }
    s[2] /= 2;
    cout << min({tre[0],tre[1],tre[2]}) << endl;
}