#include <stdio.h>
#include <string.h>


int main(void)
{
	char s[1000001];
	int tree[3] = {0};
	int min = 1000000;
	int i;

	scanf("%s", s);

	for (i = 0; i < strlen(s); i++) {
		if (s[i] == 't')
			tree[0]++;
		else if (s[i] == 'r')
			tree[1]++;
		else if (s[i] == 'e')
			tree[2]++;
	}

	tree[2] /= 2;

	for (i = 0; i < 3; i++) {
		if (min > tree[i])
			min = tree[i];
	}

	printf("%d\n", min);

	return 0;
}