#import pysnooper
#import numpy
#import os,re,sys,operator
#from collections import Counter,deque
#from operator import itemgetter
#from itertools import accumulate,combinations,groupby,combinations_with_replacement,permutations
from sys import stdin,setrecursionlimit
#from bisect import bisect_left,bisect_right
#from copy import deepcopy
#import heapq
#import math
#import string
#from time import time
#from functools import lru_cache
setrecursionlimit(10**6)
input=stdin.readline

n=int(input().rstrip())
p=[int(i) for i in input().split()]
tmp=1
for i in p:
    now=i
    while len(str(now))!=1:
        now=sum(list(map(int,str(now))))
    tmp*=now

while len(str(tmp))!=1:
    tmp=sum(list(map(int,str(tmp))))
print(tmp)