sq = {i**2:i for i in range(10**4)}

N = int(input())
S = input()
k = S.count("Q")
if not k:
    print(-1)
else:
    if not k in sq:
        print(-1)
    else:
        Q_cnt = sq[k]
        if N%Q_cnt:
            print(-1)
        else:
            L = N//Q_cnt
            T = [S[i:i+L] for i in range(0,N,L)]
            if all(T[0]==T[i] for i in range(len(T))):
                print(T[0])
            else:
                print(-1)