import sys
import itertools
import math
def S(): return sys.stdin.readline().rstrip()
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def LS(): return list(sys.stdin.readline().rstrip().split())

n = I()
a = LI()

if min(a) == 0:
    print(-1)
elif max(a) >= 4:
    print(10**9+7)
elif a.count(3) >= 4:
    print(10**9+7)
elif a.count(2) >= 16:
    print(10**9+7)
else:
    ans = 1
    for i in range(n):
        if a[i] == 2:
            ans *= 2**2
        elif a[i] == 3:
            ans *= 3**6
    print((10**9+7)%ans)