#include<iostream>
using namespace std;
int main(void)
{
	int i, t = 0, r = 0, e = 0, ans;
	char s[1000100];

	cin >> s;
	for (i = 0; s[i] != '\0'; i++) {
		if (s[i] == 't')t += 1;
		else if (s[i] == 'r')r += 1;
		else if (s[i] == 'e')e += 1;
	}
	e /= 2;

	if (t <= r&&t <= e)ans = t;
	else if (r <= t&&r <= e)ans = r;
	else ans = e;
	cout << ans << endl;
	return 0;
}