n = int(input())
s = input()

def is_square(n):
    for i in range(1, 1000):
        if n == i * i:
            return i
    return -1

if 'H' not in s:
    q = s.count('Q')

    sq = is_square(q)

    if sq != -1:
        if n % sq == 0:
            b = n // sq
            t = s[0 : b]

            check = True

            for l in range(0, n, b):
                if t != s[l : l + b]:
                    check = False

            if check:
                print(t)
                exit(0)


print(-1)