<?php
$turn_max = trim(fgets(STDIN));
$pos_array = array();
$neg_array = array();
$yes_time = 0;
for ( $turn=0; $turn<$turn_max; $turn++ ) {
	list($num_array[0], $num_array[1], $num_array[2], $num_array[3], $ans) = explode(" ", trim(fgets(STDIN)));
	$num_array = array_unique($num_array);
	if ( strcmp($ans, 'YES') == 0 ) {
		$pos_array = array_merge($pos_array, $num_array);
		$yes_time++;
	}
	else {
		$neg_array = array_merge($neg_array, $num_array);
	}
}
$result = -1;
$neg_array = array_unique($neg_array);
if ( count($neg_array) >= 9 ) {
	for ( $needle=0; $needle<=9; $needle++ ) {
		if ( array_search($needle, $neg_array) === FALSE ) {
			$result = $needle;
			break;
		}
	}
}
if ( $result == -1 ) {
	$count_array = array_count_values($pos_array);
	$max_count = 0;
	foreach ( $count_array as $num => $count ) {
		if ( ($count == $yes_time) && (array_search($num, $neg_array) === FALSE) ) {
			$max_count++;
			$result = $num;
		}
	}
}
echo $result.PHP_EOL;