#include <stdio.h>
#include <algorithm>
#include <deque>
using namespace std;
using ll = long long;

int main() {
	char s[1000001];
	scanf("%s", s);

	ll tc = 0, rc = 0, ec = 0, total = 0;
	for (int i = 0; s[i] != 0; i++) {
		if (s[i] == 't') {
			tc++;
		} else if (s[i] == 'r') {
			rc++;
		} else if (s[i] == 'e') {
			ec++;
		}
	}
	total = min(min(tc, rc), ec / 2);
	printf("%lld\n", total);
}