#include <iostream>
#include <algorithm>

using namespace std;

int main()
{
	int t, r, e;
	char S[1000000];
	cin >> S;
	for( int i = 0; S[i] != '\0'; i++ ) {
		switch( S[i] ) {
		case 't':
			t++;
			break;
		case 'r':
			r++;
			break;
		case 'e':
			e++;
			break;
		}
	}
	e = e/2;
	cout << min( min( t, r ) , e ) << endl;

	return 0;
}