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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
namespace AtCoder
{
    class Program
    {

        static void Main(string[] args)
        {
            string a = "\n", b = Console.ReadLine();
            int i = GetFunc(() => 1)();
            var mask = new []{ 1, 2, +3 };
            foreach (var item in b)
            {
                mask[
                GetFunc(() =>
                {
                    if (0 <= (i % 2 - 1)) Console.Write("{0}", item, i);
                    return (i += 1) % 2;
                })()
                ] = 1;
            }
        }
        
        static Func<T> GetFunc<T>(Func<T> func) => func; 

    }
}