import math

n = int(input())
s = input()
cnt = 0
for c in s:
    if c != "Q" and c != "+":
        print(-1)
        exit()
    if c == "Q":
        cnt += 1

m = int(math.sqrt(cnt))
if m ** 2 == cnt and n % m == 0:
    u = s[0 : n // m]
    if u * m == s:
        print(u)
    else:
        print(-1)
else:
    print(-1)