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 Java8 (OpenJDK 1.8.0) (judge verdict: Memory Limit Exceeded)

import java.util.Scanner;
public class Main {

    public static void main(String[] args){
    	Scanner sc = new Scanner(System.in);
    	// 入力
    	String s = sc.next();
    	String[] ary = s.split("", 0);
    	String ans = "";

    	for(int i = 0; i < ary.length; i++){
    		if (i % 2 == 1){
    			continue;
    		}
    		ans = ans + ary[i];
    	}
    	// 出力
    	System.out.println(ans);
    }
}