#include <stdio.h>
#include <malloc.h>

char str[60000];
int str_len = 0;

/// <summary>
/// グローバル変数strの中身を入力された文字列で上書きする
/// </summary>
void ReadString() {
	char c = getchar();
	str_len = 0;

	while (c != '\n') {
		str[str_len] = c;
		c = getchar();
		str_len++;
	}
}

int main()
{
	ReadString();
	int tree[3] = { 0,0,0 };
	for (int i = 0;i < str_len;i++) {
		if (str[i] == 't') tree[0]++;
		if (str[i] == 'r') tree[1]++;
		if (str[i] == 'e') tree[2]++;
	}
	tree[2] /= 2;
	int min = 31231231132;
	for (int i = 0;i < 3;i++) {
		if (tree[i] < min) min = tree[i];
	}
	printf("%d\n",min);
}