n = int(input())
a = list(map(int, input().split()))
mod = 10 ** 9 + 7

if any(va == 0 for va in a):
    print(-1)
if any(va > 3 for va in a):
    print(mod)

f = [1]
for i in range(3):
    f.append(f[-1] * (i + 1))
for i in range(len(f)):
    f[i] = pow(i, f[i])

ans = 1

for va in a:
    if ans > mod:
        print(mod)
        exit(0)
    else:
        ans *= f[va]

print(mod % ans)