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 <bits/stdc++.h>
using namespace std;

/* REPmacro */
#define REP(i,n) for(int i=0,i##_len=(n);i<i##_len;++i)
#define REPR(i,n) for(int i=((int)(n)-1);i>=0;--i)
#define FOR(i,m,n) for(int i=(int)(m);i<(int)(n);++i)

/*alias*/
#define ALL(x) (x).begin(),(x).end()
#define SZ(x) ((int)(x).size())
#define F first
#define S second
#define PB push_back
#define MP make_pair 

#define y0 y3487465
#define y1 y8687969
#define j0 j1347829
#define j1 j234892
#define next asdnext
#define prev asdprev

/*using*/
using ll = long long;
using ull = unsigned long long;
using unsi = unsigned;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using pii = pair<int, int>;
using db = double;
using plex = complex<double>;
using vs = vector<string>;

/*template*/
template<class T>inline bool amax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>inline bool amin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

/* func */
int gcd(int a,int b){return b?gcd(b,a%b):a;}

/*struct*/
struct aaa{
    aaa(){
        cin.tie(0); ios::sync_with_stdio(0); cout<<fixed<<setprecision(20);
    };
}aaaaaaa;

/* const */
const int INF = 1001001001;
const ll LINF = 1001001001001001001ll;
const int MOD = 1e9 + 7; //10^9
const db EPS = 1e-9;
const int dx[] = {0, 1, 0, -1, 1, -1, 1, -1}, dy[] = {1, 0, -1, 0, 1, -1, -1, 1};

//#define int ll
//#define int long long

signed main()
{
  string s; cin >> s;
  
  for(int i = 0; i < s.length(); ++i)
   if(i % 2 == 0)
    cout << s[i];
  
  return 0;
}