#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
int main() {
	cin.tie(0); ios::sync_with_stdio(false);
	int tree[3] = { 0 }; //tree[0] := t  tree[1] := r  tree[2] := e
	int ans = 0;
	string S;
	cin >> S;
	int len = S.length();
	for (int i = 0; i < len; i++) {
		if (S[i] == 't') { tree[0]++; }
		if (S[i] == 'r') { tree[1]++; }
		if (S[i] == 'e') { tree[2]++; }
	}
	int x = min(tree[0], tree[1]);
	if (tree[2] <= 2 * x) {
		ans = tree[2] / 2;
	}
	else {
		ans = x;
	}
	cout << ans << endl;
	return 0;
}