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

namespace
{
int iCnt[ 10 ];
}

int main()
{
int i;
char S[ 1000100 ];
char C;

	cin >> S;

	i = 0;
	while( C = S[ i ] )
	{
		if( C == 't' )
			iCnt[ 0 ]++;
		else if( C == 'r' )
			iCnt[ 1 ]++;
		else if( C == 'e' )
			iCnt[ 2 ]++;

		i++;
	}

	iCnt[ 2 ] /= 2;
	cout << *min_element( iCnt, iCnt + 3 ) << endl;

	return 0;
}