import math
MOD = 10**9 + 7
N = int(input())
A = list(map(int, input().split()))

for a in A:
    if a == 0:
        exit(print(-1))

ans = 1
for a in A:
    if a >= 4:
        exit(print(MOD))

    ans *= a**(math.factorial(a))

    if ans >= MOD:
        exit(print(MOD))

#print(ans)
ans2 = MOD % ans
if ans2 == 0:
    ans2 = -1
print(ans2)