#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <math.h>

int main()
{
	char str[100001] = "";
	int t = 0;
	int r = 0;
	int e = 0;
	int cnt = 0;

	scanf("%s", str);
	for (int i = 0; str[i] != '\0'; i++)
	{
		if (str[i] == 't')
		{
			t++;
		}
		else if (str[i] == 'r')
		{
			r++;
		}
		else if (str[i] == 'e')
		{
			e++;
		}
	}

	e /= 2;

	while (true)
	{
		if (t <= 0 || r <= 0 || e <= 0)
		{
			printf("%d\n", cnt);
			break;
		}

		t--;
		r--;
		e--;
	}

	return 0;
}