# coding: utf-8
# Your code here!

N=int(input())
P=list(map(int,input().split()))

temp=1
judge=False
for p in P:
    if p==0:
        print(0)
        exit()
        
    temp=(temp*p)%9
    if temp==0:
        judge=True

if judge:
    print(9)
else:
    print(temp)