Problem:
Score : 200 points

Problem Statement

You are given a string s consisting of lowercase English letters. Extract all the characters in the odd-indexed positions and print the string obtained by concatenating them. Here, the leftmost character is assigned the index 1.

Constraints

Each character in s is a lowercase English letter.

1≤|s|≤10^5

Input

The input is given from Standard Input in the following format:

s

Output

Print the string obtained by concatenating all the characters in the odd-numbered positions.

Sample Input 1

atcoder

Sample Output 1

acdr

Extract the first character a, the third character c, the fifth character d and the seventh character r to obtain acdr.

Sample Input 2

aaaa

Sample Output 2

aa

Sample Input 3

z

Sample Output 3

z

Sample Input 4

fukuokayamaguchi

Sample Output 4

fkoaaauh

Solution in PHP7 (7.0.15) (judge verdict: Accepted)

<?php

class In {

	private $buf = [];
	private $count = 0;
	private $pointer = 0;

	public function nextLine() {
		$ret = '';
		if($this->hasNext()){
			while($this->hasNext()){
				$ret .= $this->next();
			}
		}else{
			$ret = trim(fgets(STDIN));
		}

		return $ret;
	}

	public function next() {
		if(!$this->hasNext()) {
			$str = trim(fgets(STDIN));
			$this->buf = explode(' ',$str);
			$this->count = count($this->buf);
			$this->pointer = 0;
		}

		return $this->buf[$this->pointer++];
	}

	public function hasNext() {
		return $this->pointer < $this->count;
	}

	public function nextInt() {
		return (int)$this->next();
	}

	public function nextDouble() {
		return (double)$this->next();
	}
}

class Out {
	public function println($str = '') {
		echo $str . PHP_EOL;
	}
}

$in = new In();
$out = new Out();

$s = $in->next();
$len = strlen($s);

$ans = '';
for ($i = 0;$i < $len;$i+=2) {
	$ans .= $s[$i];
}

$out->println($ans);

?>