N = int(input())
S = input()
if "H" in S:
  print(-1)
  exit(0)
Q = S.count("Q")
if Q == 1:
  print(S)
  exit(0)
qsqrt = 0
for x in range(1, N):
  if x ** 2 == Q:
    qsqrt = x
    break
else:
  print(-1)
  exit(0)
substring = ""
for x in range(1, N):
  if x * Q == N:
    substring = S[: x]
    break
if substring == "":
  print(-1)
  exit(0)
print(substring * qsqrt)