#include <iostream>
#include <algorithm>
#include <regex>
using namespace std;

int main(){

    string s;
    cin >> s;
	int l = s.size();
 	int t = 0, r = 0, e = 0;
  	for ( int i = 0; i < l; i++ ){
    	if ( s[i] == 't' ) t++ ;
        if ( s[i] == 'r' ) r++ ;
        if ( s[i] == 'e' ) e++ ;
    }
    cout << min( {t, r, e/2} ) << endl;
  	

    return 0;
}