#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<cstdio>
using namespace std;
int n,l=1,r,j,k;
char a[2010];
int main(){
	freopen("bcl.in","r",stdin);
	freopen("bcl.out","w",stdout);
	scanf("%d",&n);r=n;
	for(int i=1;i<=n;++i)cin>>a[i];
	for(int i=1;i<=n;++i){
		if(i%80==1&&i!=1)cout<<endl;
		for(j=l,k=r;j<=k;j++,k--) {
			if(a[j]<a[k]){cout<<a[l];++l;break;}
			else{
				if(a[j]>a[k]){printf("%c",a[r]);--r;break;}
			    else if(j==k||j+1==k){printf("%c",a[l]);++l;break;}
			}
		}
	}
	return 0;
}