//
//  main.cpp
//  testprogram
//
//  Created by Yan Olerinskiy on 05/09/2019.
//  Copyright © 2019 Yan Olerinskiy. All rights reserved.
//

#include <iostream>
#include <vector>
#include <string>
#include <iomanip>
#include <queue>
#include <cmath>
#include <algorithm>
#include <tuple>
#include <iomanip>
#include <stdio.h>
#include <numeric>
#include <map>
#include <bitset>
#include <set>
#include <stack>
#include <queue>

//#pragma GCC optimize("Ofast,no-stack-protector")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC optimize("fast-math")
//#pragma GCC optimize("section-anchors")
//#pragma GCC optimize("profile-values,profile-reorder-functions,tracer")
//#pragma GCC optimize("vpt")
//#pragma GCC optimize("rename-registers")
//#pragma GCC optimize("move-loop-invariants")
//#pragma GCC optimize("unswitch-loops")
//#pragma GCC optimize("function-sections")
//#pragma GCC optimize("data-sections")
//#pragma GCC optimize("branch-target-load-optimize")
//#pragma GCC optimize("branch-target-load-optimize2")
//#pragma GCC optimize("btr-bb-exclusive")

#define int long long
#define ll long long
#define ull unsigned long long
#define all(a) a.begin(), a.end()
#define pii pair<int, int>
#define pb push_back
#define ld long double

using namespace std;

const int INF = 1e13;
//const int mod = 2600000069;
//const int p = 179;

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
//    freopen("points.in", "r", stdin);
//    freopen("points.out", "w", stdout);
    string s;
    cin >> s;
    int n = s.size();
    string ans(n, ' ');
    for (int i = 0; i < n/2; i++) {
        ans[i * 2 + 1] = s[i];
    }
    int cur = 0;
    for (int i = n/2; i < n; i++, cur += 2) {
        ans[cur] = s[i];
    }
    cout << ans;
}