#include<iostream>
#include<string>
using namespace std;

string s;
int num[256];

int main(){
	cin >> s;
	for( int i = 0; i < s.length(); i++ )
		num[s[i]]++;
	
	int ans = 1145140;
	ans = min(ans, num['t']);
	ans = min(ans, num['r']);
	ans = min(ans, num['e']/2);
	
	cout << ans << endl;
	return 0;
}