#include <stdio.h>

int main(void)
{
	char s[1000001];
	scanf("%s", s);
	int i = 0, j[3] = { 0 };
	while (s[i] != '\0') {
		if (s[i] == 't') j[0]++;
		if (s[i] == 'r') j[1]++;
		if (s[i] == 'e') j[2]++;
		i++;
	}
	j[2] /= 2;
	for (int k = 0; k < 2; k++) {
		for (int l = 2; l > k; l--) {
			if (j[l] < j[l - 1]) {
				int t = j[l];
				j[l] = j[l - 1];
				j[l - 1] = t;
			}
		}
	}
	printf("%d\n", j[0]);
	return 0;
}