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

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

	int tree[3] = { 0 };

	for (int 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] = (tree[2] - tree[2] % 2) / 2;

	int min = tree[0];

	if (min > tree[1])
	{
		min = tree[1];
	}

	if (min > tree[2])
	{
		min = tree[2];
	}

	printf("%d", min);

	return 0;
}