#include <iostream>
#include <algorithm>
#include <map>

#include <vector>

using namespace std;

int main() {
	
	string s;
	cin >> s;
	int arr[3] = {0,0,0};
	for(char it:s) {
	    if(it == 't') arr[0]++;
	    else if(it == 'r') arr[1]++;
	    else if(it == 'e') arr[2]++;
	}
	arr[2] /= 2;
	cout << *min_element(begin(arr), end(arr));
	return 0;
}