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: Accepted)

#include <iostream>
#include <string>
using namespace std; //头文件和命名空间
int main(){
    ios::sync_with_stdio(false); //输入输出加速
    string sInput; //输入的字符串
    int i; //循环计数器
    cin >> sInput; //读入
    for (i = 0; i < sInput.length(); i+=2){ //枚举奇数位置，注意由于string中第一个字符的索引号为0，因此题目的奇数位事实上是字符串中索引号为偶数的位置
        cout << sInput[i]; //输出对应位置的字符，注意string中第一个字符的索引号为0
    }
    cout << endl; //换行
    return 0; //结束
}