Repeating Cipher

Repeating cipher is used for strings. To encrypt the string $s = s_{1} s_{2} \dots s_{m}$ ( $1 \leq m \leq 10$ ), 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" $\to$ "baa" $\to$ "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 $n$ ( $1 \leq n \leq 55$ ) — 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

#include <bits/stdc++.h>

using namespace std;

int main() {

int n;

cin >> n;

string s;

cin >> s;

string ans;

int temp = 0;

for (int i = 0; i < n; i += temp) {

ans += s[i];

temp++;

}

cout << ans << endl;

return 0;

}

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