check1

source.cpp

#include <iostream>
#include <algorithm>
#include <string>

using namespace std;

int main()
{
    string str;
    getline(cin, str);
    int n;
    cin >> n;
    for (int it = 0; it < n; ++it)
    {
        string str2;
        string str3;

        for (int i = 0; i < str.length(); ++i)
        {
            if (i % 2 == 0)
                str2 += str[i];
            else
                str3 += str[i];
        }

        std::reverse(str2.begin(), str2.end());
        std::reverse(str3.begin(), str3.end());

        str = str3 + str2;

        cout << str << endl;
    }

    int m;
    cin >> m;
    return 0;
}

source.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            int n;
            String str = "";
            str = Console.ReadLine();
            n = int.Parse(Console.ReadLine());
            
            for (int it = 0; it < n; ++it)
            {
                string str2 = "";
                string str3 = "";

                for (int i = 0; i < str.Length; ++i)
                {
                    if (i % 2 == 0)
                        str2 += str[i];
                    else
                        str3 += str[i];
                }

                str2 = new String(str2.Reverse().ToArray());
                str3 = new String(str3.Reverse().ToArray());
                str = str3 + str2;

                Console.WriteLine(str);
            }

            Console.ReadLine();

        }
    }
}

source.java

import java.io.EOFException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Task1
{   
    public static void main(String... args)
    {	
    	Scanner scan = new Scanner(System.in);
    	String str;
    	str = scan.nextLine();
    	int n;
    	n = scan.nextInt();
    	
    	for (int it = 0; it < n; ++it)
    	{
    		String str2 = "";
    		String str3 = "";
    		
    		for (int i = 0; i < str.length(); ++i)
    		{
    			if (i % 2 == 0)
    				str2 += str.toCharArray()[i];
    			else
    				str3 += str.toCharArray()[i];
    		}
    		StringBuffer buf = new StringBuffer(str2);
    		StringBuffer buf2 = new StringBuffer(str3);
    		str2 = buf.reverse().toString();
    		str3 = buf2.reverse().toString();
    		
    		str = str3 + str2;
    		
    		System.out.println(str);
    	}
    }
}