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;

typedef long long ll;
typedef unsigned long long ull;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define REP(i,n) for(int i=0;i<(n);i++)
#define RREP(i,n) for(int i=(n)-1;i>=0;i--)
#define VSORT(v) sort(v.begin(), v.end())
#define DVSORT(v) sort(v.begin(), v.end(),greater<int>())
#define SORT(v, n) sort(v, v+n)
#define DSORT(v,n) sort(v, v+n,greater<int>())
#define vi vector<int>
#define pb push_back
#define P pair<int,int>


template <class T> void chmin(T&a, const T&b) { a = min(a,b); }
template <class T> void chmax(T&a, const T&b) { a = max(a,b); }

const double EPS =1e-9;
const long INF =999999999;
const long MOD =1000000007; //10^9+7
#define PI 3.14159265258979

int dy[]={0, 0, 1, -1, 1, 1, -1, -1};
int dx[]={1, -1, 0, 0, 1, -1, -1, 1};

int main(void){
	int i;
	string S;
	cin>>S;

	i=0;
	while(S[i]!='\0'){
		if(i%2==0) cout<<S[i];
		i++;
	}
	puts("");
	return 0;
}