use strict;
use warnings;

my $s = <>;
chomp $s;
my @str = split //, $s;
my @count;

for(my $i = 0; $i < 3; $i++) {
	$count[$i] = 0; 
}

for(my $i = 0; $i < $#str + 1; $i++) {
	if($str[$i] eq 't') {
		$count[0]++;
	} elsif($str[$i] eq 'r') {
		$count[1]++;
	} elsif($str[$i] eq 'e') {
		$count[2]++;
	}
}
$count[2] /= 2;
$count[2] = int $count[2];

@count = sort {$a <=> $b} @count;

print "$count[0]\n";

exit;