#include <iostream>
#include <string>

using namespace std;
#define MIN(a,b) ((a)<(b)?(a):(b))

int main()
{
	int t[3] = { 0 };
	string s; cin >> s;

	for (int i = 0; i < s.size(); i++) {
		if (s[i] == 't') t[0]++;
		if (s[i] == 'r') t[1]++;
		if (s[i] == 'e') t[2]++;
	}
	t[2] /= 2;

	cout << MIN(t[0], MIN(t[1], t[2])) << endl;

	return 0;
}