#include <bits/stdc++.h>
using namespace std;

int main()
{
	string S;
	cin >> S;

	int tcnt = 0;
	int rcnt = 0;
	int ecnt = 0;
	for( int i = 0; i < S.size(); i++ ) {
		if( S[i] == 't' ) tcnt++;
		if( S[i] == 'r' ) rcnt++;
		if( S[i] == 'e' ) ecnt++;
	}
	int ans = min( tcnt, min( rcnt, ecnt / 2 ) );

	cout << ans << endl;
}