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 Java (OpenJDK 11.0.6) (judge verdict: Accepted)

import java.io.BufferedReader;
import java.io.InputStreamReader;

import java.util.Arrays;
import java.util.Collections;
import java.util.ArrayList;
import java.util.List;
import java.util.HashSet;
import java.io.PrintWriter;
import java.io.OutputStream;
import java.util.Comparator;

public class Main {
    // 標準入力
    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    // 標準入力数値配列用 int
    static int[] inputval() throws Exception {
        String[] strarray = br.readLine().trim().split(" ");
        int[] intarray = new int[strarray.length];
        for (int i = 0; i < intarray.length; i++) {
            intarray[i] = Integer.parseInt(strarray[i]);
        }
        return intarray;
    }

    // 標準入力数値リスト用 int
    static List<Integer> inputIntList() throws Exception {
        List<String> strList = Arrays.asList(br.readLine().trim().split(" "));
        List<Integer> intList = new ArrayList<Integer>();
        for (String elem : strList){
            intList.add(Integer.parseInt(elem));
        }
        return intList;
    }

    // 標準入力数値配列用 integer ソート用
    static Integer[] inputvalInteger() throws Exception {
        String[] strarray = br.readLine().trim().split(" ");
        Integer[] intarray = new Integer[strarray.length];
        for (int i = 0; i < intarray.length; i++) {
            intarray[i] = Integer.parseInt(strarray[i]);
        }
        return intarray;
    }

    public static void main(String[] args) throws Exception {
        // write your code here
        String s = br.readLine();
        StringBuilder ans = new StringBuilder();
        for (int i=0; i<s.length(); i++){
            if (i%2 == 0){
                ans.append(s.charAt(i));
            }
        }
        System.out.println(ans.toString());

    }

}