import sys
def I(): return int(sys.stdin.readline().rstrip())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))  #空白あり


N = I()
A = LI()
m = 10**9+7

if min(A) == 0:
    print(-1)
    exit()

if max(A) >= 4:
    print(m)
else:
    x = 1
    for a in A:
        if a == 2:
            x *= 4
        if a == 3:
            x *= 729
        if x > m:
            print(m)
            break
    else:
        print(m % x)