#include<stdio.h>
#include<string.h>
int main()
{
	char s[1000006];
	scanf("%s", s);
	int i, n = strlen(s);
	int t, r, e;
	t = r = e = 0;
	for (i = 0; i < n; i++)
	{
		if (s[i] == 't')t++;
		if (s[i] == 'r')r++;
		if (s[i] == 'e')e++;
	}
	int ans = t;
	if (ans > r)ans = r;
	if (ans > e / 2)ans = e / 2;
	printf("%d\n", ans);
	return 0;
}