Problem:
Score : 200 points

Problem Statement

You are given a string S consisting of lowercase English letters.
We will write down this string, starting a new line after every w letters. Print the string obtained by concatenating the letters at the beginnings of these lines from top to bottom.

Constraints

1 \leq w \leq |S| \leq 1000

S consists of lowercase English letters.

w is an integer.

Input

Input is given from Standard Input in the following format:

S
w

Output

Print the desired string in one line.

Sample Input 1

abcdefgh
3

Sample Output 1

adg

When we write down abcdefgh, starting a new line after every three letters, we get the following:

abc

def

gh

Concatenating the letters at the beginnings of these lines, we obtain adg.

Sample Input 2

lllll
1

Sample Output 2

lllll

Sample Input 3

souuundhound
2

Sample Output 3

suudon

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

using System;
using System.Text;

namespace B {
    class Program {
        static void Main(string[] args) {
            string S = Console.ReadLine();
            int w = int.Parse(Console.ReadLine());

            var tmp = S.ToCharArray();
            StringBuilder ans = new StringBuilder();
            for (int i = 0; i < S.Length; ++i) {
                if (i % w == 0) ans.Append(tmp[i]);
            }

            Console.WriteLine(ans.ToString());
        }
    }
}