Problem: Polycarp loves ciphers. He has invented his own cipher called repeating.

Repeating cipher is used for strings. To encrypt the string s=s_{1}s_{2} ... s_{m} (1 ≤ m ≤ 10), Polycarp uses the following algorithm:

  * he writes down s_1 ones, 
  * he writes down s_2 twice, 
  * he writes down s_3 three times, 
  * ... 
  * he writes down s_m m times. 



For example, if s="bab" the process is: "b" → "baa" → "baabbb". So the encrypted s="bab" is "baabbb".

Given string t — the result of encryption of some string s. Your task is to decrypt it, i. e. find the string s.

Input

The first line contains integer n (1 ≤ n ≤ 55) — the length of the encrypted string. The second line of the input contains t — the result of encryption of some string s. It contains only lowercase Latin letters. The length of t is exactly n.

It is guaranteed that the answer to the test exists.

Output

Print such string s that after encryption it equals t.

Examples

Input


6
baabbb


Output


bab

Input


10
ooopppssss


Output


oops

Input


1
z


Output


z

Solution (in JAVA):

Solution:
import java.io.*;
import java.util.*;



 public class A
{
    static int MOD = 1000000007;
    static FastReader in = new FastReader();
    static PrintWriter p = new PrintWriter(System.out, true);



    static int solve(){
        int n = in.nextInt();
        char[] arr = new char[n + 1];
        String s = in.next();
        for(int i = 1; i < n + 1; i++){
            arr[i] = s.charAt(i - 1);
        }
        int place = 1;
        for(int i = 1; i < arr.length; i += place++){
            p.print(arr[i]);
        }

        p.println();
        p.close();
        return 0;
    }

    public static void main(String[] args)
    {
        solve();
    }

    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader()
        {
            br = new BufferedReader(
                    new InputStreamReader(System.in));
        }

        String next()
        {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() { return Integer.parseInt(next()); }

        long nextLong() { return Long.parseLong(next()); }

        double nextDouble()
        {
            return Double.parseDouble(next());
        }

        String nextLine()
        {
            String str = "";
            try {
                str = br.readLine();
            }
            catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }

    static class F{


        static void swap(int[] a, int i, int j){
            int temp = a[i];
            a[i] = a[j];
            a[j] = temp;
        }

        static void swap(String[] a, int i, int j){
            String temp = a[i];
            a[i] = a[j];
            a[j] = temp;
        }

        static void swap(long[] a, int i, int j){
            long temp = a[i];
            a[i] = a[j];
            a[j] = temp;
        }

        static void swap(double[] a, int i, int j){
            double temp = a[i];
            a[i] = a[j];
            a[j] = temp;
        }

        static int[] readArrI(int N){
            int[] res = new int[N];
            for (int i = 0; i < N; i++){
                res[i] = in.nextInt();
            }
            return res;
        }

        static String[] readArrS(int N){
            String[] res = new String[N];
            for (int i = 0; i < N; i++){
                res[i] = in.next();
            }
            return res;
        }

        static double[] readArrD(int N){
            double[] res = new double[N];
            for (int i = 0; i < N; i++){
                res[i] = in.nextDouble();
            }
            return res;
        }

        static long[] readArrL(int N){
            long[] res = new long[N];
            for (int i = 0; i < N; i++){
                res[i] = in.nextLong();
            }
            return res;
        }

        static char[] readArrC(int N){
            char[] res = new char[N];
            for (int i = 0; i < N; i++){
                res[i] = in.next().charAt(0);
            }
            return res;
        }

        static int bisect_right(int[] A, int x) {
            return bisect_right(A, x, 0, A.length);
        }

        static int bisect_right(int[] A, int x, int lo, int hi) {
            int N = A.length;
            if (N == 0) {
                return 0;
            }
            if (x < A[lo]) {
                return lo;
            }
            if (x > A[hi - 1]) {
                return hi;
            }
            for (;;) {
                if (lo + 1 == hi) {
                    return lo + 1;
                }
                int mi = (hi + lo) / 2;
                if (x < A[mi]) {
                    hi = mi;
                } else {
                    lo = mi;
                }
            }
        }

        static int bisect_left(int[] A, int x) {
            return bisect_left(A, x, 0, A.length);
        }

        static int bisect_left(int[] A, int x, int lo, int hi) {
            int N = A.length;
            if (N == 0) {
                return 0;
            }
            if (x < A[lo]) {
                return lo;
            }
            if (x > A[hi - 1]) {
                return hi;
            }
            for (;;) {
                if (lo + 1 == hi) {
                    return x == A[lo] ? lo : (lo + 1);
                }
                int mi = (hi + lo) / 2;
                if (x <= A[mi]) {
                    hi = mi;
                } else {
                    lo = mi;
                }
            }
        }
    }

    static class Pair<A,B>{
        A first;
        B second;
        Pair(A a, B b){
            first = a;
            second = b;
        }
    }
}