/*
ID: espr1t
TASK: 
KEYWORDS: 
*/

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>

using namespace std;
FILE *in; FILE *out;

const int MAX = 10004;
const int LEN = 10000;

int n;
char a[MAX];


int main(void) {
	in = stdin; out = stdout;
	in = fopen("code.in", "rt"); out = fopen("code.out", "wt");
	
	fscanf(in, "%d %s", &n, a);
	
	string ans;
	int left = 0, right = n - 1;
	while (left <= right) {
	    if (a[left] < a[right]) {
	        ans += a[left++];
	    } else if (a[right] < a[left]) {
	        ans += a[right--];
	    } else {
	        string sLeft, sRight;
	        for (int i = 0; i < min(LEN, right - left + 1); i++)
	            sLeft += a[left + i];
	        for (int i = 0; i < min(LEN, right - left + 1); i++)
	            sRight += a[right - i];
	        if (sLeft < sRight)
	            ans += a[left++];
	        else
	            ans += a[right--];
	    }
	}
	fprintf(out, "%s\n", ans.c_str());
	
	return 0;
}