#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);

    string s; cin >> s;
    int t = 0, r = 0, ee = 0;
    rep(i,s.size()){
        t += (s[i] == 't');
        r += (s[i] == 'r');
        ee += (s[i] == 'e');
    }

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