#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(n);++i)
#define ALL(A) A.begin(), A.end()
#define INF (1<<20)

using namespace std;

typedef long long ll;
typedef pair<int, int> P;

int cnt[26];

int main()
{
	memset(cnt, 0, sizeof(cnt));
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	string S; cin >> S;
	
	int n = S.length();
	rep (i, n){
		++cnt[(int)(S[i] - 'a')];
	} // end rep

	int res = INF;
	res = min(res, cnt[(int)('t'-'a')]);
	res = min(res, cnt[(int)('r'-'a')]);
	res = min(res, cnt[(int)('e'-'a')] / 2);

	cout << res << endl;

	return 0;
}