import sys

N = int(input())
S = input()

qnum = 0
for i in S:
    if i == "H":
        print (-1)
        sys.exit()
    elif i == "Q":
        qnum += 1

for i in range(1000):
    if i ** 2 == qnum:
        rp = i
        break
else:
    print (-1)
    sys.exit()

if qnum == 0:
    print (-1)
    sys.exit()

code = S[:N//rp]
#print (code)

for i in range(N):

    if S[i] != code[i % len(code)]:
        print (-1)
        sys.exit()

print (code)