import sys
input=sys.stdin.readline
def I(): return int(input())
def MI(): return map(int, input().split())
def LI(): return list(map(int, input().split()))

def main():
    mod=10**9+7
    N=I()
    A=LI()
    
    if min(A)==0:
        print(-1)
        exit()
        
    inf=10**10
    res=1
    for i in range(N):
        a=A[i]
        if a>=4:
            res=inf
            break
        else:
            temp=1
            for j in range(1,a+1):
                temp*=j
            res*=pow(a,temp)
        if res>=mod:
            break
        
    print(mod%res)
        
    
        
    
    


main()