#include <iostream>
#include <sstream>
#include <math.h>
#include <stack>
#include <set>
#include <algorithm>
#include <string>
#include <queue>
#include <stack>
#include <map>
#include <cstdio>
#include <vector>
using namespace std;

#define INF (1 << 30)
#define INFLL (1LL << 60)

int main() {
	string str;
	int t = 0,r = 0,e = 0;
	cin >> str;
	for(int i = 0;i < str.size();i++){
		if(str[i] == 't') t++;
		if(str[i] == 'r') r++;
		if(str[i] == 'e') e++;
	}
	e = e/2;
	cout << min(t,min(r,e)) << endl;
	return 0;
}