#include<iostream>
#include<string>
#include<string.h>
#include<algorithm>
#include<stdio.h>
#include<cmath>
#include<vector>
#include<utility>
#define FOR(i, a, b) for(int i=(a);i<=(b);i++)
#define RFOR(i, a, b) for(int i=(a);i>=(b);i--)
#define MOD 1000000007

using namespace std;


int main(void) {
	string s;
	int ct = 0, cr = 0, ce = 0;
	cin >> s;
	FOR(i, 0, s.size() - 1) {
		if (s[i] == 't') {
			ct++;
		}
		if (s[i] == 'r') {
			cr++;
		}
		if (s[i] == 'e') {
			ce++;
		}
	}
	ce /= 2;
	cout << min(ct, min(cr, ce)) << endl;
	return 0;
}