Problem:
Sorting Pairs

Write a program which print coordinates $(x_i, y_i)$ of given $n$ points on the plane by the following criteria.

first by $x$-coordinate

in case of a tie, by $y$-coordinate

Input

The input is given in the following format.

$n$
$x_0 \; y_0$
$x_1 \; y_1$
:
$x_{n-1} \; y_{n-1}$

In the first line, the number of points $n$ is given. In the following $n$ lines, coordinates of each point are given.

Output

Print coordinate of given points in order.

Constraints

$1 \leq n \leq 100,000$

$-1,000,000,000 \leq x_i, y_i \leq 1,000,000,000$

Sample Input 1

5
4 7
5 5
2 3
6 8
2 1

Sample Output 1

2 1
2 3
4 7
5 5
6 8

Solution in PHP (judge verdict: Accepted)

<?php
$numbers = fgets(STDIN);
$n = intval($numbers);
// print $n;
$array = [];
for($i = 0; $i < $n; $i++){
    $numbers = preg_split("/[\s,]+/", rtrim(fgets(STDIN)));
    $array[] = array('one' => $numbers[0], 'two'=>$numbers[1]);
}
foreach( $array as $value) {
    $one_array[] = $value['one'];
    $two_array[] = $value['two'];
}

array_multisort( $one_array, SORT_ASC, SORT_NUMERIC, $two_array, SORT_ASC, SORT_NUMERIC, $array);
foreach( $array as $v) {
    echo $v['one'] . " ". $v['two'];
    echo PHP_EOL;
}