#include <iostream>
#include <string>
#include <algorithm>
#include <functional>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <bitset>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
using namespace std;
typedef long long ll;
typedef pair<int,int> pint;
typedef vector<int> vint;
typedef vector<pint> vpint;
#define mp make_pair
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define reps(i,f,n) for(int i=(f);i<(n);i++)
int dx[4] = {1, 0, 0, -1};
int dy[4] = {0, 1, -1, 0};

int main(void){
	string s; cin >> s;
	int size = s.size();
	int t = 0, r = 0, e = 0;
	rep(i, size){
		if(s[i] == 't') t++;
		else if(s[i] == 'r') r++;
		else if(s[i] == 'e') e++;
	}

	e /= 2;
	int ans = min(t, min(r, e));
	printf("%d\n", ans);
	return 0;
}