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 Scanner
{
    private $arr = [];
    private $count = 0;
    private $pointer = 0;

    public function next()
    {
        if ($this->pointer >= $this->count) {
            $str = trim(fgets(STDIN));
            $this->arr = explode(" ", $str);
            $this->count = count($this->arr);
            $this->pointer = 0;
        }
        $result = $this->arr[$this->pointer];
        $this->pointer++;
        return $result;
    }

    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 static function printIn($str = "")
    {
        echo $str . PHP_EOL;
    }
}

$sc = new Scanner;

$s = $sc->next();
$s_arr = str_split($s);

//for ($i = 0; $i < count($s_arr); $i++) {
//  if ($i === 0 || $i % 2 === 0){
//      echo $s_arr[$i];
//  }
//}

for ($i = 0; $i < count($s_arr); $i += 2) {
    echo $s_arr[$i];
}