https://codeforces.com/contest/1087/problem/A

题解：模拟

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=10000;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m,k,q;
string str , ans;
int main()
{
#ifdef DEBUG
	freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
#endif
    //scanf("%d",&n);
    cin>>str;
    int n=str.size();
    //ans[0]=str[0];
    int x=0,y=n-1;
    for(int i=n-1;i>=0;i--){
        if(i%2==0){
            ans=str[x++]+ans;
        }else{
            ans=str[y--]+ans;
        }
    }
    cout << ans << endl;
    //cout << "Hello world!" << endl;
    return 0;
}