from math import factorial
n = int(input())
a = [int(i) for i in input().split()]
if max(a) >= 4:
    print(-1)
    exit()
ans = 1
mod = 10 ** 9 + 7

for i in a:
    ans *= pow(i, factorial(i))
    if ans >= mod:
        print(-1)
        exit()
print(mod % ans)