#define _USE_MATH_DEFINES
 
#include <iostream>
#include <iomanip>
#include <sstream>
 
#include <algorithm>
#include <cmath>
 
#include <string>
#include <queue>
#include <vector>
#include <complex>
#include <set>
#include <map>
#include <stack>
#include <list>
 
/////////
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i,n) REP(i,0,n)
#define P(p) cout<<(p)<<endl;
 
#define PII pair<int,int>
/////////
typedef long long LL;
typedef long double LD;
/////////
using namespace::std;
/////////
int num[26];
void solve(){
	int nMin = 0;
	string str;
	cin >> str;
	int N = str.size();
	nMin = N;
	for(int i=0;i<N;++i) {
		++num[ str[i] - 'a'];
	}
	nMin = min(nMin,num['t'-'a'] );
	nMin = min(nMin,num['r'-'a'] );
	nMin = min(nMin,num['e'-'a']/2 );
	cout << nMin << endl;
}

int main(void){
    std::cin.tie(0); 
    std::ios::sync_with_stdio(false);
    std::cout << std::fixed;//
    //cout << setprecision(16);//
	
	//cpp
	solve();
	return 0;
}