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

typedef long long int           ll;
typedef unsigned long long int  ull;
typedef vector<int>             vi;
typedef vector<ll>              vll;
typedef vector<vi>              vvi;
typedef pair<int,int>           pii;
typedef vector< pii >           vpii;
typedef set<int>                sti;

#define pb                      push_back
#define pob                     pop_back
#define mp                      make_pair
#define ff                      first
#define ss                      second
#define loop1(i,n)              for(int i=1; i<=int(n); i++)
#define loop(i,y)               for(int i=0; i<int(y); i++)
#define rloop(i,y)              for(int i=int(y); i>0; i--)
#define rloop1(i,y)             for(int i=int(y)-1; i>=0; i--)
#define read()                  freopen("input.txt", "r", stdin)
#define write()                 freopen("output.txt", "w", stdout)
#define cspf(i)                 printf("Case %d: ", i)
#define all(v)                  v.begin(),v.end()
/// Constants
#define eps                     1e-9
#define PI                      acos(-1.0)  // 3.1415926535897932

int main()
{
    char s[100],st[100];
    scanf("%s",s);
    int ln=strlen(s);
    int x;
    if(ln<=2){
        printf("%s\n",s);
        return 0;
    }
    x=ln/2;
    if(ln%2==0)
        x--;
    int i=0;
    int prev=x-1;
    int next=x+1;
    st[i]=s[x];
    i++;
    while(i<ln){
        if(i%2==1){
            st[i]=s[next];
            next++;
            i++;
            continue;
        }
        if(i%2==0){
            st[i]=s[prev];
            prev--;
            i++;
            continue;
        }
    }
    st[i]='\0';
    printf("%s\n",st);
    return 0;
}