/* -*- coding: utf-8 -*-
 *
 * 3132.cc:  No.3132 證怜捷繝｡繝・そ繝ｼ繧ｸ - yukicoder
 */

#include<cstdio>
#include<algorithm>

using namespace std;

/* constant */

const int MAX_N = 100000;

/* typedef */

/* global variables */

int ds[MAX_N];

/* subroutines */

/* main */

int main() {
  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%d", ds + i);
  sort(ds, ds + n);

  for (int i = 0; i < n; i++) putchar('A' + ds[i] % 26);
  putchar('\n');
  
  return 0;
}