#include<iostream>
#include<algorithm>
#include<vector>
#include<set>
#include<string>
#include<sstream>
#include<cctype>
#include<functional>
#include<iomanip>
using namespace std;

int main()
{
	int a[3] = {};
	char b[3] = { 't', 'r', 'e' };
	string s;
	cin >> s;
	for (int i = 0; i < static_cast<int>(s.size()); i++)
	{
		if (s[i] == b[0])a[0]++;
		else if (s[i] == b[1])a[1]++;
		else if (s[i] == b[2])a[2]++;
	}
	cout << min(a[0], min(a[1], a[2] / 2)) << endl;
	return 0;
}