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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>
#include<string.h>
#include<math.h>
int main()
{
	char a[10010];
	int i,j,t,m,n,q,p;
	while(scanf("%d",&q)!=EOF)
	{
		getchar();
		for(p=0;p<q;p++)
		{
	        gets(a);
        	m=strlen(a);
        	n=sqrt(m);
        	if(m==n*n)
	        {
        	for(i=0;i<n;i++)
	            for(j=0;j<n;j++)
    	        {
	            	t=i+j*n;
	            	putchar(a[t]);
	            }
        	}
        	else printf("INVALID");
        	printf("\n");
		}
    }
	return 0;
}