import math
MOD = 10**9 + 7
n = int(input())
a = list(map(int, input().split()))
if any(v == 0 for v in a):
    print(-1)
    exit()
if max(a) > 3:
    print(MOD)
    exit()
else:
    ans = 1
    for v in a:
        ans *= pow(v, math.factorial(v))
        if ans > MOD:
            print(MOD)
            exit()
    print(MOD % ans)
    exit()