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;

class Program
{
  static void Main(string[] args)
  {
    string S = Console.ReadLine();
    int N = S.Length;
    char[] A = new char[(N + 1) / 2];

    for (int i = 0; i < N; ++i)
    {
      if (i % 2 == 0)
      {
        A[i / 2] = S[i];
      }
    }

    string ans = new string(A);

    Console.WriteLine(ans);
  }
}