Problem:
Score : 200 points

Problem Statement

You are given a string s consisting of lowercase English letters. Extract all the characters in the odd-indexed positions and print the string obtained by concatenating them. Here, the leftmost character is assigned the index 1.

Constraints

Each character in s is a lowercase English letter.

1≤|s|≤10^5

Input

The input is given from Standard Input in the following format:

s

Output

Print the string obtained by concatenating all the characters in the odd-numbered positions.

Sample Input 1

atcoder

Sample Output 1

acdr

Extract the first character a, the third character c, the fifth character d and the seventh character r to obtain acdr.

Sample Input 2

aaaa

Sample Output 2

aa

Sample Input 3

z

Sample Output 3

z

Sample Input 4

fukuokayamaguchi

Sample Output 4

fkoaaauh

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <iostream>
#include <cstring>
#include <cmath>
#include <cstdio>
using namespace std;
int main()
{
    int n,m,t;
    cin >> n;
    getchar();
    while(n--)
    {
        int i,j;
        char b[100000],a[100][101];
        cin.getline(b,100000);
        m=strlen(b);
        t = sqrt(m);
        if(pow(t,2)!=m)
            cout << "INVALID" ;
        else
        {
            int c=0;
            while(c!=m)
            {
                for( i = 0; i < t; i++)
                for( j = 0; j < t; j++)
                    a[i][j]=b[c++];
            }
            for(i=0;i<t;i++)
                for(j=0;j<t;j++)
            cout << a[j][i] ;
        }
        cout << endl;
    }
    return 0;
}