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: Accepted)

#include<iostream>
#include<cmath>
#include<vector>
#include<set>
#include<algorithm>
#include<tuple>
#include<utility>
#include<cctype>
#include<climits>
#include<map>
#include<queue>
#include<functional>

using namespace std;
template<class T> void chmax(T& a, T b) {if(a < b){a=b;}}
template<class T> void chmin(T& a, T b) {if(a > b){a=b;}}

#define REP(i,a,n) for(int i=a;i<n;++i)
#define RUP(a,b) ((a+b-1)/(b))
#define ENT "\n"
#define REV(v) reverse(v.begin(),v.end())
#define SRTV(v) sort(v.begin(),v.end())
#define SRTA(a,n) sort(a,a+n)
#define MOD 1000000007

typedef long long ll;
typedef tuple<int,int,bool> Tb;

int atcoder(){
    //入力
    string s;
  	cin >> s;
    string ans = "";
    //処理
    REP(i,0,s.length()){
      if(i%2==0) ans += s[i];
    }
    
    //出力
    cout << ans << ENT;
    return 0;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    atcoder();
    return 0;
}