#!/usr/bin/php

<?php

// Usage: cat [input file] | php [this file]

$networkSize = fscanf(STDIN, '%d')[0];
$network = array_pad([], $networkSize, []);
// At this point, the network is an array where keys are computers' ID and
// values are empty arrays, which will be used to store the list of computers
// the key is wired to

// Wiring the network
for ($readLines = 0; $readLines < $networkSize - 1; $readLines++) {
    $line = fscanf(STDIN, '%d %d');
    array_push($network[$line[0]], $line[1]);
    array_push($network[$line[1]], $line[0]);
}
// $network = array( [2],  [2],  [0 1 3],  [2 4 6],  [3 5],  [4],  [3] )

// foreach ($network as $index => $reach) {
//     echo 'C' . $index . ' --> [ ' . implode('  ', $reach) . '  ]' . PHP_EOL;
// } die();

$prof = array_pad([], $networkSize, 0);

// By butting the wire between $from and $to, returns the importance of $from
// in its sub-network (found by recursively cutting more wires)
// Also the importance of each computer in this sub-network is sored in $prof
function find(int $from, int $to)
{
    global $network, $prof;
    $importance = 1;
    foreach ($network[$from] as $computerWithInternet) {
        if ($computerWithInternet !== $to) {
            $importance += find($computerWithInternet, $from);
        }
    }
    $prof[$from] = $importance;
    return $importance;
};

// echo find(3, 2) . PHP_EOL;
// foreach ($prof as $i => $x) {
//     echo 'C' . $i . ' -> ' . $x . PHP_EOL;
// } die();

// find(2, 3);
// find(2, 5);
// echo '[' . implode(', ', $prof) . ']' . PHP_EOL;



$mini = 1000000000;

function find2(int $from, int $to, int $wS)
{
    global $mini, $network, $prof;
    $v = $w;
    foreach ($network[$from] as $computer) {
        if ($computer != $to) {
            $v = max([$v, $prof[$computer]]);
            find2($computer, $from, $w + $prof[$from] - $prof[$computer]);
        }
    }
    $mini = min($mini, $v);
}

find(0, -1);
find2(0, -1, 0);
// foreach ($prof as $i => $x) {
//     echo 'C' . $i . ' -> ' . $x . PHP_EOL;
// } die();
echo $mini . PHP_EOL;















// -------- DEBUG ------------------

function printNetwork(array $net)
{
    foreach ($net as $sub) {
        echo implode(' - ', $sub) . PHP_EOL;
    }
}