#include<iostream>
#include<string>
#include<cstring>
#include<complex>
#include<vector>
#include<algorithm>
#include<cstdlib>
#include<cmath>
#include<iomanip>
using namespace std;

#define REP(i, j) for (int i = 0; i < (int)j; ++i)
#define FOR(i, j, k) for (int i = (int)j; i < (int)k; ++i)
#define SORT(v) sort(v.begin(), v.end())
#define REVERSE(v) reverse(v.begin(), v.end())
typedef complex<double> P;
typedef vector<int> VI;
typedef long long LL;
typedef pair<int,int> PII;

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	string s;
	cin >> s;

	VI tree(3, 0);
	REP(i,s.length()) {
		if (s[i] == 't') tree[0]++;
		if (s[i] == 'r') tree[1]++;
		if (s[i] == 'e') tree[2]++;
	}
	tree[2] /= 2;
	SORT(tree);
	cout << tree[0] << endl;

	return 0;
}