#include <iostream>
#include <algorithm>
#include <functional>
#include <string>
#include <climits>
#include <vector>
#include <numeric>
#include <complex>
#include <map>
#include <bitset>
#include <stack>
#include <queue>
using namespace std;

//#define __int64 long long
#define long __int64
#define REP(i,a,b) for(int i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)
const int Vecy[4] = {0,-1,0,1};
const int Vecx[4] = {1,0,-1,0};
const int modd = 1000000007;

int main(){
	string s;
	int cnt[3] = {0};
	
	cin >> s;
	rep(i,s.length()){
    	if(s[i] == 't'){
			cnt[0] += 2;
    	}else if(s[i] == 'r'){
			cnt[1] += 2;
    	}else if(s[i] == 'e'){
			cnt[2] ++;
    	}
	}
	
	cout << min(cnt[0], min(cnt[1], cnt[2])) / 2 << endl;
	
    return 0;
}