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

int main(){
	string str;
	cin >> str;
	int count_t = 0, count_r = 0, count_e = 0;
	int ans = 0;
	for(int i = 0; i < str.size(); i++){
		if(str[i] == 't') count_t++;
		if(str[i] == 'r') count_r++;
		if(str[i] == 'e') count_e++;
	}
	while(count_t > 0 and count_r > 0 and count_e > 1){
		count_t--;
		count_r--;
		count_e -= 2;
		ans++;
	}
	cout << ans << endl;
	return 0;
}