n = int(input())
A = list(map(int, input().split()))
import math
A.sort()
if A[0] == 0:
    print(-1)
elif max(A) >= 4:
    print(10**9+7)
else:
    t = 1
    for a in A:
        t *= a**math.factorial(a)
        if t >= 10**9+7:
            print(10**9+7)
            exit()
    else:
        print((10**9+7)%t)