#include <iostream>
#include <cmath>
#include <string>
#include <vector>
#include <map>
#include <set>
#include <list>
#include <deque>
#include <algorithm>
#include <iomanip>
#include <functional>

#define REP(i, n) for(int i = 0;i < (n); i++)
#define REP2(i, x, n) for(int i = (x); i < (n); i++)
#define REPR(i, n) for(int i = (n); i >= 0; i--)

#define ALL(a) (a).begin(),(a).end()
#define SORT(c) sort((c).begin(),(c).end())

#define LL long long
#define LD long double

#define PI 3.14159265358979

using namespace std;
//============================================
// 二分探索
int binary_search(vector<int>ary, int key, int imin, int imax) {
	if (imax < imin) {
		return -1;
	} else {
		int imid = imin + (imax - imin) / 2;
		if (ary[imid] > key) {
			return binary_search(ary, key, imin, imid - 1);
		} else if (ary[imid] < key) {
			return binary_search(ary, key, imid + 1, imax);
		} else {
			return imid;
		}
	}
}

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

	string S;
	cin >> S;

	int tCount = 0, rCount = 0, eCount = 0;
	REP(i, S.size()) {
		switch (S[i]) {
			case 't' :
				tCount++;
				break;
			case 'r':
				rCount++;
				break;
			case 'e':
				eCount++;
				break;
		}
	}

	int ans = 0;
	while (tCount >= 1 && rCount >= 1 && eCount >= 2) {
		tCount--;
		rCount--;
		eCount -= 2;
		ans++;
	}

	cout << ans << "\n";
	return 0;
}