import collections,sys,math,functools,operator,itertools,bisect,heapq,decimal,string,time,random
#sys.setrecursionlimit(10**9)
#sys.set_int_max_str_digits(0)
#input = sys.stdin.readline
n = int(input())
a = list(map(int,input().split()))
#alist = []
#s = input()
#n,m = map(int,input().split())
#for i in range(n):
#    alist.append(list(map(int,input().split())))
ans = []
for i in range(n):
    ans.append((a[i],chr(ord('A') + a[i] % 26)))
ans.sort()
for i,j in ans:
    print(j,end='')
print()