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 CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
long long int ll_max(long long int a, long long int b, long long int c) {
  return max(a, max(b, c));
}
int int_max(int a, int b, int c) { return max(a, max(b, c)); }
long long int ll_min(long long int a, long long int b, long long int c) {
  return min(a, min(b, c));
}
int int_min(int a, int b, int c) { return min(a, min(b, c)); }
long long int max(int a, long long int b) { return max((long long int)a, b); }
long long int min(int a, long long int b) { return min((long long int)a, b); }
long long int min(long long int a, int b) { return min(a, (long long int)b); }
long long int max(long long int a, int b) { return max(a, (long long int)b); }
long long int dx[] = {0, 0, 1, -1};
long long int dy[] = {1, -1, 0, 0};
long long int power(long long int x, long long int y, long long int m) {
  if (y == 0) return 1;
  long long int a = power(x, y / 2, m);
  if (y % 2) {
    return (a * ((a * x) % m)) % m;
  } else {
    return (a * a) % m;
  }
}
long long int mod_inverse(long long int x, long long int m) {
  return power(x, m - 2, m);
}
long long int fact(long long int n, long long int m) {
  if (n <= 1) return 1;
  return (fact(n - 1, m) * n) % m;
}
long long int ncr(long long int n, long long int r, long long int m) {
  if (r > n) return 0;
  long long int n1 = 1, d1 = 1, d2 = 1;
  n1 = fact(n, m);
  d1 = fact(r, m);
  d2 = fact(n - r, m);
  long long int ans = mod_inverse((d1 * d2) % m, m);
  ans = (ans * n1) % m;
  return ans;
}
int gcd(int a, int b) {
  if (a < b) return gcd(b, a);
  if (a % b == 0) return b;
  return gcd(b, a % b);
}
int ispal(string s) {
  int len = s.size();
  int flag = 1;
  for (int i = 0; i < len; ++i) {
    if (s[i] != s[len - i - 1]) {
      flag = 0;
      break;
    }
  }
  return flag;
}
long long int sroot(long long int n, long long int low = 1,
                    long long int high = 1e9 + 1) {
  if (low == high) return low;
  if (low == high - 1) {
    if (high * high <= n)
      return high;
    else
      return low;
  }
  long long int mid = (low + high) / 2;
  long long int a = mid * mid;
  if (a > n)
    return sroot(n, low, mid - 1);
  else
    return sroot(n, mid, high);
}
long long int croot(long long int n, long long int low = 1,
                    long long int high = 1e6 + 1) {
  if (low == high) return low;
  if (low == high - 1) {
    if (high * high * high <= n)
      return high;
    else
      return low;
  }
  long long int mid = (low + high) / 2;
  long long int a = mid * mid * mid;
  if (a > n)
    return croot(n, low, mid - 1);
  else
    return croot(n, mid, high);
}
bool sortbysec(const pair<long long int, long long int> &a,
               const pair<long long int, long long int> &b) {
  return (a.second < b.second);
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long int n;
  cin >> n;
  string str;
  cin >> str;
  long long int c = 1;
  string res = "";
  for (long long int i = 0; i < n;) {
    res += str[i];
    i += c;
    c++;
  }
  cout << res;
  return 0;
}