#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <math.h>

using namespace std;
int main()
{
	string s;
	cin >> s;
	int t = 0;
	int r = 0;
	int e = 0;
	for(int i = 0; i < s.size(); i++)
	{
		if(s[i] == 't') t++;
		if(s[i] == 'r') r++;
		if(s[i] == 'e') e++;
	}

	cout << min(t, min(r, e/2));
	return 0;
}