n = int(input())
S = input()
for s in S:
    if not(s == "Q" or s == "+"):
        print(-1)
        exit()
q = S.count("Q")
for i in range(10**3):
    if i*i == q:
        break
else:
    print(-1)
    exit()
print(i)
if n%i:
    print(-1)
    exit()
m = n//i
P = S[:m]
if S == P*i:
    print(P)
else:
    print(-1)