MOD = 1000000007

def main():
    _ = int(input())
    res = 1
    f = [1,1,2,6]
    for v in map(int,input().split()):
        if 1 <= v <= 3:
            res *= pow(v, f[v])
            if res > MOD:
                print(MOD)
                return
        elif v:
            print(MOD)
            return
        else:
            print(-1)
            return
    print(MOD%res)


if __name__ == "__main__":
    main()