<?php

$total = 0;
$input = trim(file_get_contents("input.txt"));
$groups = preg_split('/\n\n/', $input);

foreach ( $groups as $group )
{
	$answered_yes = [];
	$people_in_group = 0;
	
	$people = preg_split('/\n/', $group);
	
	foreach ( $people as $person )
	{
		for ( $i = 0; $i < strlen($person); ++$i )
		{
			++$answered_yes[$person{$i}];
		}
		
		++$people_in_group;
	}
	
	foreach ( $answered_yes as $k => $v )
	{
		if ( $v == $people_in_group )
		{
			++$total;
		}
	}
}

print "$total\n";