def digit(n):
    if n==0:
        return 0
    q=str(n)
    tmp=0
    for i in range(len(q)):
        tmp+=int(q[i])
    if tmp%9!=0:
        tmp%=9
    else:
        tmp=9
    return  tmp

n=int(input())
p=list(map(int,input().split()))
ct=1
for i in range(n):
    ct*=p[i]

ans=digit(ct)
print(ans)